Form 485BPOS Calamos ETF Trust

As filed with the U.S. Securities and Exchange Commission on November 21, 2024

Securities Act File No. 333-191151

Investment Company Act File No. 811-22887

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT

If appropriate, check the following box:

☐ This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

CALAMOS ETF TRUST

CONTENTS OF POST EFFECTIVE AMENDMENT NO. 50

This Registration Statement consists of the following papers and documents:

Cover Sheet

Part A – Prospectus – Calamos Convertible Equity Alternative ETF, Calamos CEF Income & Arbitrage ETF, and Calamos Alternative Nasdaq^® & Bond ETF

Part B – Statements of Additional Information

Part C – Other Information

Signature Page

Exhibit Index

Calamos Convertible Equity Alternative ETF
(NYSE Arca—CVRT)

Prospectus December 2, 2024

Calamos Convertible Equity Alternative ETF (the "Fund") is a series of the Calamos ETF Trust (the "Trust") and an exchange-traded fund ("ETF"). The Fund lists and principally trades its shares on the NYSE Arca, Inc. ("NYSE Arca" or the "Exchange").

The U.S. Securities and Exchange Commission ("SEC") has not approved or disapproved these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Table of Contents

Calamos Convertible Equity Alternative ETF

Investment Objective

Fees and Expenses of the Fund

Annual Fund Operating Expenses (ongoing expenses that you pay each year as a percentage of the value of your investments):

Example

Portfolio Turnover

Principal Investment Strategies

Calamos Convertible Equity Alternative ETF

Principal Risks

An investment in the Fund is subject to risks, and you could lose money on your investment in the Fund. There can be no assurance that the Fund will achieve its investment objective. You should not consider investing in the Fund if your investment objective differs from the Fund's investment objective or if you are not willing to accept the principal risks associated with an investment in the Fund. The risks associated with an investment in the Fund can increase during times of significant market volatility. Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a "principal risk" of investing in the Fund, regardless of the order in which it appears. The principal risks of investing in the Fund include:

•  Authorized Participant Concentration Risk — Only an Authorized Participant may engage in creation or redemption transactions directly with the Fund, and none of those Authorized Participants is obligated to engage in creation and/or redemption transactions. The Fund has a limited number of institutions that may act as Authorized Participants on an agency basis (i.e., on behalf of other market participants). To the extent that Authorized Participants exit the business or are unable to proceed with creation or redemption orders with respect to the Fund and no other Authorized Participant is able to step forward to create or redeem, Fund Shares may be more likely to trade at a premium or discount to NAV and possibly face trading halts or delisting. Authorized Participant concentration risk may be heightened for ETFs, such as the

Calamos Convertible Equity Alternative ETF

Fund, that invest in securities issued by non-U.S. issuers or other securities or instruments that have lower trading volumes.

•  Convertible Securities Risk — The value of a convertible security is influenced by changes in interest rates, with investment value declining as interest rates increase and increasing as interest rates decline. The credit standing of the issuer and other factors also may have an effect on the convertible security's investment value. Convertible securities generally offer lower interest or dividend yields than non-convertible fixed-income securities of similar credit quality because of the potential for capital appreciation. In addition, the value of a convertible security is influenced by the interest rate environment, company credit risk, and by the value of the underlying common stock. As the market price of the underlying common stock declines below the conversion price, the price of the convertible security tends to be increasingly influenced by the credit quality, maturity and yield of the convertible security. Holders of convertible securities have a claim on the issuer's assets prior to the common stockholders, but may be subordinated to holders of similar but non-convertible securities of the same issuer.

•  Costs of Buying and Selling Fund Shares — Due to the costs of buying or selling Fund Shares, including brokerage commissions imposed by brokers and bid/ask spreads, frequent trading of Fund Shares may significantly reduce investment results and an investment in Fund Shares may not be advisable for investors who anticipate regularly making small investments.

•  Debt Securities Risk — Debt securities are subject to various risks, including interest rate risk, credit risk and default risk.

•  Interest Rate Risk — The value of debt securities generally decreases in periods when interest rates are rising. In addition, interest rate changes typically have a greater effect on prices of longer-term debt securities than shorter term debt securities. Recent fixed-income market events, including increases in volatility and interest rates, may expose the Fund to heightened interest rate risk and volatility.

•  Credit Risk — A debt security could deteriorate in quality to such an extent that its rating is downgraded or its market value declines relative to comparable securities. Changes in actual or perceived creditworthiness may occur quickly. If the Fund holds securities that have been downgraded, or that default on payment, the Fund's performance could be negatively affected.

•  Default Risk — A company that issues a debt security may be unable to fulfill its obligation to repay principal and interest. The lower a bond is rated, the greater its default risk. To the extent the Fund holds securities that have been downgraded, or that default on payment, its performance could be negatively affected.

•  Equity Securities Risk — The securities markets are volatile, and the market prices of the Fund's securities may decline generally. The price of equity securities fluctuates based on changes in a company's financial condition and overall market and economic conditions. If the market prices of the securities owned by the Fund fall, the value of your investment in the Fund will decline.

•  Foreign Securities Risk — Risks associated with investing in foreign securities include fluctuations in the exchange rates of foreign currencies that may affect the U.S. dollar value of a security, the possibility of substantial price volatility as a result of political and economic instability in the foreign country, less public information about issuers of securities, different securities regulation, different accounting, auditing and financial reporting standards and less liquidity than in U.S. markets.

•  High Yield Risk — High yield securities and unrated securities of similar credit quality (commonly known as "junk bonds") are subject to greater levels of credit and liquidity risks. High yield securities are considered primarily speculative with respect to the issuer's continuing ability to make principal and interest payments.

•  Large-Capitalization Investing Risk — Large-capitalization stocks as a group could fall out of favor with the market, which may cause a Fund to underperform funds that focus on other types of stocks. In addition, larger, more established companies may be unable to respond quickly to new competitive challenges such as changes in technology and consumer preferences. Many larger companies also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

Calamos Convertible Equity Alternative ETF

•  Market Maker Risk — If the Fund has lower average daily trading volumes, it may rely on a small number of third-party market makers to provide a market for the purchase and sale of Fund Shares. Any trading halt or other problem relating to the trading activity of these market makers could result in a dramatic change in the spread between the Fund's net asset value and the price at which the Fund Shares are trading on the Exchange, which could result in a decrease in value of the Fund Shares. In addition, decisions by market makers or authorized participants to reduce their role or step away from these activities in times of market stress could inhibit the effectiveness of the arbitrage process in maintaining the relationship between the underlying values of the Fund's portfolio securities and the Fund's market price. This reduced effectiveness could result in Fund Shares trading at a discount to net asset value and also in greater than normal intra-day bid-ask spreads for Fund Shares.

•  Market Risk — The risk that the securities markets will increase or decrease in value is considered market risk and applies to any security. If there is a general decline in the stock or fixed-income market, it is possible your investment may lose value regardless of the individual results of the companies in which the Fund invests.

•  National Closed Market Trading Risk — To the extent that the underlying securities and/or other assets held by the Fund trade on non-U.S. exchanges or in non-U.S. markets that may be closed when the securities exchange on which Fund Shares trade is open, there are likely to be deviations between the current price of such an underlying security and the last quoted price for the underlying security (i.e., the Fund's quote from the closed non-U.S. market). The impact of a closed foreign market on the Fund is likely to be greater where a large portion of the Fund's underlying securities and/or other assets trade on that closed non-U.S. market or when the non-U.S. market is closed for unscheduled reasons. These deviations could result in premiums or discounts to the Fund's NAV that may be greater than those experienced by other ETFs.

•  New Fund Risk — The Fund is a recently organized investment company with a limited operating history. As a result, prospective investors have a limited track record or history on which to base their investment decision.

•  Non-Diversification Risk — The Fund is classified as "non-diversified" under the 1940 Act. As a result, the Fund is only limited as to the percentage of its assets which may be invested in the securities of any one issuer by the diversification requirements imposed by the Internal Revenue Code of 1986, as amended.

•  Options Risk — The Fund's ability to close out its position as a purchaser or seller of an over-the-counter or exchange-listed put or call option is dependent, in part, upon the liquidity of the option market. There are significant differences between the securities and options markets that could result in an imperfect correlation among these markets, causing a given transaction not to achieve its objectives. The Fund's ability to utilize options successfully will depend on the ability of the Fund's investment adviser to predict pertinent market movements, which cannot be assured.

•  Portfolio Selection Risk — The value of your investment may decrease if Calamos Advisors' judgment about the attractiveness, value or market trends affecting a particular security, issuer, industry or sector or about market movements is incorrect.

•  Portfolio Turnover Risk — The portfolio managers may actively and frequently trade securities or other instruments in the Fund's portfolio to carry out its investment strategies. A high portfolio turnover rate increases transaction costs, which may increase the Fund's expenses. Frequent and active trading may also cause adverse tax consequences for investors in the Fund due to an increase in short-term capital gains.

•  Premium-Discount Risk — Fund Shares may trade above or below their net asset value ("NAV"). The market prices of Fund Shares will generally fluctuate in accordance with changes in NAV as well as the relative supply of, and demand for, Fund Shares on the Exchange. The trading price of Fund Shares may deviate significantly from NAV during periods of market volatility.

•  Rule 144A Securities Risk — The Fund may invest in securities that are issued and sold through transactions under Rule 144A of the Securities Act of 1933. Under the supervision of its board of trustees, the Fund will determine whether Rule 144A Securities are illiquid. If qualified institutional buyers are unwilling to purchase these Rule 144A Securities, the percentage of the Fund's assets invested in illiquid securities would increase. Typically, the Fund purchases Rule 144A Securities if the Fund's adviser has determined them to be liquid. If any Rule 144A Security held by the Fund should become illiquid, the value of the security may be reduced and a sale of the security may be more difficult.

Calamos Convertible Equity Alternative ETF

•  Secondary Market Trading Risk — Investors buying or selling Fund Shares in the secondary market will pay brokerage commissions or other charges imposed by brokers as determined by that broker. Brokerage commissions are often a fixed amount and may be a significant proportional cost for investors seeking to buy or sell relatively small amounts of Fund Shares. Although the Fund Shares are listed on the Exchange, there can be no assurance that an active or liquid trading market for them will develop or be maintained. In addition, trading in Fund Shares on the Exchange may be halted.

•  Sector Risk — To the extent the Fund invests a significant portion of its assets in a particular sector, a greater portion of the Fund's performance may be affected by the general business and economic conditions affecting that sector. Each sector may share economic risk with the broader market, however there may be economic risks specific to each sector. As a result, returns from those sectors may trail returns from the overall stock market, and it is possible that the Fund may underperform the broader market or experience greater volatility.

•  Securities Lending Risk — The Fund may lend its portfolio securities to broker-dealers and banks in order to generate additional income for the Fund. Any such loan must be continuously secured by collateral in cash or cash equivalents maintained on a current basis in an amount at least equal to the market value of the securities loaned by the Fund. In the event of bankruptcy or other default of a borrower of portfolio securities, the Fund could experience both delays in liquidating the loan collateral or recovering the loaned securities and losses, including (a) possible decline in the value of the collateral or in the value of the securities loaned during the period while the Fund seeks to enforce its rights thereto, (b) possible subnormal levels of income and lack of access to income during this period, and (c) expenses of enforcing its rights. In an effort to reduce these risks, the Fund's securities lending agent monitors, and reports to Calamos Advisors on, the creditworthiness of the firms to which the Fund lends securities. The Fund may also experience losses as a result of a diminution in value of its cash collateral investments.

•  Small and Mid-Sized Company Risk — Small and mid-sized company stocks have historically been subject to greater investment risk than large company stocks. The risks generally associated with these companies include more limited product lines, markets and financial resources, lack of management depth or experience, dependency on key personnel, and vulnerability to adverse market and economic developments. Accordingly, the prices of mid-sized company stocks tend to be more volatile than prices of large company stocks. Further, the prices of small company stocks are often adversely affected by limited trading volumes and the lack of publicly available information.

•  Synthetic Convertible Instruments Risk — The value of a synthetic convertible instrument will respond differently to market fluctuations than a convertible security because a synthetic convertible instrument is composed of two or more separate securities, each with its own market value. In addition, if the value of the underlying common stock or the level of the index involved in the convertible component falls below the exercise price of the warrant or option, the warrant or option may lose all value.

•  Trading Issues Risk — Trading in Fund Shares on the Exchange may be halted due to market conditions or for reasons that, in the view of the Exchange, make trading in shares inadvisable. In addition, trading in Fund Shares on the Exchange is subject to trading halts caused by extraordinary market volatility pursuant to the Exchange's "circuit breaker" rules. There can be no assurance that the requirements of the Exchange necessary to maintain the listing of the Fund will continue to be met or will remain unchanged. The Fund may have difficulty maintaining its listing on the Exchange in the event the Fund's assets are small, the Fund does not have enough shareholders, or if the Fund is unable to proceed with creation and/or redemption orders.

Fund Performance

Calamos Convertible Equity Alternative ETF

Investment Adviser

Calamos Advisors LLC ("Calamos Advisors" or the "Adviser")

Portfolio Managers

Other Important Information Regarding Fund Shares

Portfolio Holdings. The Fund's portfolio holdings are disclosed on its website daily after the close of trading on the Exchange and prior to the opening of trading on the Exchange the following day. A description of the Fund's policies and procedures with respect to the disclosure of the Fund's portfolio holdings is available in the Fund's Statement of Additional Information ("SAI").

Premium/Discount Information. Information about the premiums and discounts at which the Fund's Shares have traded will be available at www.calamos.com.

Purchase and Sale of Fund Shares

The Fund will issue (or redeem) Fund Shares to certain institutional investors (typically market makers or other broker-dealers) only in large blocks of Fund Shares known as "Creation Units." Creation Unit transactions are conducted in exchange for the deposit or delivery of a designated portfolio of in-kind securities and/or cash.

Individual Fund Shares may only be purchased and sold on the Exchange, other national securities exchanges, electronic crossing networks and other alternative trading systems through your broker-dealer at market prices. Because Fund Shares trade at market prices rather than at net asset value ("NAV"), Fund Shares may trade at a price greater than NAV (premium) or less than NAV (discount). When buying or selling Fund Shares in the secondary market, you may incur costs attributable to the difference between the highest price a buyer is willing to pay to purchase Fund Shares (bid) and the lowest price a seller is willing to accept for Fund Shares (ask) (the "bid-ask spread"). Recent information regarding the Fund's NAV, market price, premiums and discounts, and bid-ask spreads is available at https://www.calamos.com/.

Tax Information

Net investment income and capital gains distributions you receive from the Fund generally are subject to federal income taxes and may also be subject to state and local taxes. The Fund intends to distribute net investment income, if any, monthly, and capital gains, if any, at least annually.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase shares of the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies may pay the intermediary for the sale of Fund Shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary's website for more information.

Additional Information About Investment Strategies
and Related Risks

The Fund's investment objective, the 80% investment strategy and each of the policies described herein are non-fundamental policies that may be changed by the Board of Trustees of the Trust (the "Board") without shareholder approval. The Fund may liquidate and terminate at any time without shareholder approval.

What are the investment objective and principal strategies for the Fund?

The Fund's investment objective is total return through capital appreciation and current income.

The Fund is an actively managed exchange-traded fund ("ETF") that invests in the segment of the U.S. convertibles marketplace that has a higher level of equity sensitivity. The Fund seeks to achieve its objective by investing at least 80% of its net assets (plus borrowings for investment purposes, if any) in a portfolio of convertible securities (including synthetic convertible instruments). The Fund's investment adviser is Calamos Advisors LLC ("Calamos Advisors" or the "Adviser").

The Adviser utilizes a quantitative and qualitative screening process that consists of a proprietary convertible model and fundamental inputs to identify securities that meet the criteria for inclusion in the portfolio and intends to rebalance the portfolio regularly to ensure that the desired exposures are maintained. The Adviser will also make active adjustments to the portfolio based on fundamental analyses (such as an issuer's financial soundness, ability to make interest and dividend payments, earnings and cash flow forecast and quality of management), as well as certain portfolio-level characteristics, such as size of an issue (e.g., value of bonds outstanding), liquidity, trade execution, and exposure to macro-level investment themes.

Convertible debt securities are exchangeable for equity securities of the issuer at a predetermined price, and typically offer greater appreciation potential than non-convertible debt securities. The convertible securities in which the Fund may invest consist of U.S. bonds, structured notes, debentures and preferred stocks, which may be converted or exchanged at a stated or determinable exchange ratio into underlying shares. Structured notes are fixed-income debentures linked to equity. Convertible structured notes have the attributes of a convertible security, however, the investment bank that issued the convertible note assumes the credit risk associated with the investment, rather than the issuer of the underlying common stock into which the note is convertible. The bonds, structured notes and debentures may be rated investment grade or below investment grade or may not be rated, may be issued by corporations, governments or public international bodies and may be denominated in a variety of currencies and issued with either fixed or floating rates. Bonds rated below investment grade are commonly known as "junk bonds." Convertible securities may offer higher income than the shares into which they are convertible. The Fund may be required to permit the issuer of a convertible security to redeem the security, convert it into the underlying shares or sell it to a third party. Convertible securities include debt obligations and preferred stock of the company issuing the security, which may be exchanged for a predetermined price (the conversion price), into the issuer's common stock.

The Fund may invest up to 20% of its net assets in foreign securities. Foreign securities are securities issued by issuers that are organized under the laws of a foreign country or that have a substantial portion of their operations or assets in a foreign country or countries, or that derive a substantial portion of their revenue or profits from businesses, investments or sales outside of the United States. The Fund may also invest in foreign securities that are represented in the United States securities markets by American Depositary Receipts ("ADRs") or similar depository arrangements. The Fund's foreign securities can be denominated in U.S. dollars or in foreign currencies. Debt securities issued by a foreign government may not be supported by the "full faith and credit" of that government.

Certain convertible debt securities include a "put option" which entitles the Fund to sell the security to the issuer before maturity at a stated price, which may represent a premium over the stated principal amount of the debt security. Conversely many convertible securities are issued with a "call" feature that allows the security's issuers to choose when to redeem the security.

A synthetic convertible instrument is designed to simulate the economic characteristics of a convertible security through the combined features of a debt instrument and a security providing an option on an equity security. The Fund may establish a synthetic convertible instrument by combining a fixed-income security (which may be either convertible or non-convertible)

Additional Information About Investment Strategies and Related Risks

with the right to acquire an equity security. The fixed-income and equity option components may have different issuers, and either component may change at any time.

The Fund is classified as "non-diversified" under the Investment Company Act of 1940 (the "1940 Act").

Changes in 80% policy

The Fund has adopted a non-fundamental operating policy that requires it, under normal circumstances, to invest at least 80% of the Fund's net assets (plus borrowings for investment purposes, if any) in convertible securities. Although this requirement may be changed by the Board of Trustees without shareholder approval, the Fund will notify shareholders in writing at least 60 days prior to any change in its 80% policy.

Fund Investments

Principal Investments

Convertible Securities (including Synthetic Convertible Instruments)

The Fund invests in convertible securities (including synthetic convertible instruments). Convertible securities include, but are not limited to, any corporate debt security, debentures, notes or preferred stock that may be converted into equity securities of companies around the world, including in emerging markets. A synthetic convertible instrument is designed to simulate the economic characteristics of a convertible security through the combined features of a debt instrument and a security providing an option on an equity security. The Fund may establish a synthetic convertible instrument by combining a fixed-income security (which may be either convertible or non-convertible) with the right to acquire an equity security. The fixed-income and equity option components may have different issuers, and either component may change at any time.

In addition, the value of a convertible security is influenced by the interest rate environment, company credit risk, and by the value of the underlying common stock. The value of a convertible security viewed without regard to its conversion feature (i.e., strictly on the basis of its yield) is sometimes referred to as its "investment value." A convertible security's investment value tends to decline as prevailing interest rate levels increase. Conversely, a convertible security's investment value increases as prevailing interest rate levels decline. However, a convertible security's market value will also be influenced by its "conversion value," which is the market value of the underlying common stock that would be obtained if the convertible security were converted. A convertible security's conversion value tends to increase as the price of the underlying common stock increases, and decrease as the price of the underlying common stock decreases.

As the market price of the underlying common stock declines below the conversion price, the price of the convertible security tends to be increasingly influenced by the credit quality, maturity and yield of the convertible security. Thus, it may not decline in price to the same extent as the underlying common stock.

If the market price of the underlying common stock increases to a point where the conversion value approximates or exceeds the investment value, the price of the convertible security tends to be influenced more by the market price of the underlying common stock. In the event of a liquidation of the issuing company, holders of convertible securities would be paid before the company's common stockholders. Consequently, the issuer's convertible securities entail less risk than its common stock.

Equity Securities

The Fund invests in equity securities, including common stock. Common stock represents an equity ownership interest in issuers. Holders of common stock are entitled to the income and increase in the value of the assets and business of the issuers after all debt obligations and obligations to preferred stockholders are satisfied.

Non-Principal Investments

Cash Equivalents and Short-Term Investments

The Fund may invest in securities with maturities of less than one year or cash equivalents, or it may hold cash. The percentage of the Fund invested in such holdings varies and depends on several factors, including market conditions. For temporary defensive purposes and during periods of high cash inflows or outflows, the Fund may invest part or all of its assets in these securities or it may hold cash. During such periods, the Fund may not be able to achieve its investment objective. The Fund may adopt a defensive strategy when the portfolio managers believe securities in which such Fund normally invests have elevated

Additional Information About Investment Strategies and Related Risks

risks due to political or economic factors and in other extraordinary circumstances. For more information on eligible short-term investments, see the SAI.

Illiquid Investments

The Fund may invest up to 15% of its net assets in securities and other instruments that are, at the time of investment, illiquid (determined using the Securities and Exchange Commission's standard applicable to investment companies, i.e., any investment that the Fund reasonably expects cannot be sold or disposed of in current market conditions in seven calendar days or less without the sale or disposition significantly changing the market value of the investment). For this purpose, illiquid investments may include, but are not limited to, certain restricted securities (securities the disposition of which is restricted under the federal securities laws), certain securities that may only be resold pursuant to Rule 144A under the Securities Act, and certain repurchase agreements, among others.

Risks of Investing in the Fund

This prospectus describes the risks you may face as an investor in the Fund. It is important to keep in mind that generally, investments with a higher potential reward also have a higher risk of losing money. The reverse is also commonly true: the lower the risk, the lower the potential reward. However, as you consider an investment in the Fund, you should also take into account your tolerance for the daily fluctuations of the financial markets and whether you can afford to leave your money in this investment for a long period of time to ride out down periods.

As with any security, there are market and investment risks associated with your investment in the Fund. The value of your investment will fluctuate over time, and it is possible to lose money. The principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a "principal risk" of investing in the Fund, regardless of the order in which it appears.

In response to market, economic, political, or other conditions, the Fund may temporarily invest for defensive purposes that are inconsistent with the Fund's principal investment strategies. If the Fund does so, different factors could affect the Fund's performance, and the Fund may not achieve its investment objective.

Principal Risks

Authorized Participant Concentration Risk. Only an Authorized Participant may engage in creation or redemption transactions directly with the Fund, and none of those Authorized Participants is obligated to engage in creation and/or redemption transactions. The Fund has a limited number of institutions that may act as Authorized Participants on an agency basis (i.e., on behalf of other market participants). To the extent that Authorized Participants exit the business or are unable to proceed with creation or redemption orders with respect to the Fund and no other Authorized Participant is able to step forward to create or redeem, Fund Shares may be more likely to trade at a premium or discount to NAV and possibly face trading halts or delisting. Authorized Participant concentration risk may be heightened for ETFs, such as the Fund, that invest in securities issued by non-U.S. issuers or other securities or instruments that have lower trading volumes.

Convertible Securities Risk. The value of a convertible security is influenced by both the yield of non-convertible securities of comparable issuers and by the value of the underlying common stock. The value of a convertible security viewed without regard to its conversion feature (i.e., strictly on the basis of its yield) is sometimes referred to as its "investment value." A convertible security's investment value tends to decline as prevailing interest rate levels increase. Conversely, a convertible security's investment value increases as prevailing interest rate levels decline. However, a convertible security's market value will also be influenced by its "conversion value," which is the market value of the underlying common stock that would be obtained if the convertible security were converted. A convertible security's conversion value tends to increase as the price of the underlying common stock increases, and decrease as the price of the underlying common stock decreases.

As the market price of the underlying common stock declines such that the conversion value is substantially below the investment value of the convertible security, the price of the convertible security tends to be influenced more by the yield of the convertible security. Thus, it may not decline in price to the same extent as the underlying common stock.

Additional Information About Investment Strategies and Related Risks

If the market price of the underlying common stock increases to a point where the conversion value approximates or exceeds the investment value, the price of the convertible security tends to be influenced more by the market price of the underlying common stock. In the event of a liquidation of the issuing company, holders of convertible securities would be paid before the company's common stockholders. Consequently, the issuer's convertible securities entail less risk than its common stock.

Costs of Buying and Selling Fund Shares. Due to the costs of buying or selling Fund Shares, including brokerage commissions imposed by brokers and bid/ask spreads, frequent trading of Fund Shares may significantly reduce investment results and an investment in Fund Shares may not be advisable for investors who anticipate regularly making small investments.

Debt Securities Risk. Debt securities are subject to various risks, including interest rate risk, credit risk and default risk.

Interest Rate Risk. Interest rate risk is the risk that the Fund's investments in debt securities will decrease in value as a result of an increase in interest rates. Generally, there is an inverse relationship between the value of a debt security and interest rates. Therefore, the value of debt securities generally decrease in periods when interest rates are rising. In addition, interest rate changes typically have a greater effect on prices of longer-term debt securities than shorter-term debt securities. Recent fixed-income market events, including changes in interest rates by the Federal Reserve Board, may subject the Fund to heightened interest rate risk as a result of a rise in interest rates. In addition, the Fund is subject to the risk that interest rates may exhibit increased volatility, which could cause the Fund's net asset value to fluctuate more. A decrease in fixed-income market maker capacity may act to decrease liquidity in the fixed-income markets and act to further increase volatility, affecting the Fund's return. Many financial instruments use or may use a floating rate which historically has been based on the London Interbank Offered Rate ("LIBOR"), which was the offered rate for short-term Eurodollar deposits between major international banks. In connection with the global transition away from LIBOR led by regulators and market participants, LIBOR was last published on a representative basis at the end of June 2023. Actions by regulators have resulted in the establishment of alternative reference rates to LIBOR, such as the Secured Overnight Financing Rate (SOFR), and the transition to new reference rates continues. The transition away from LIBOR and the use of replacement rates has gone relatively smoothly, but the full impact of the transition away from LIBOR on the Fund or the financial instruments in which the Fund invests cannot yet be fully determined.

Credit Risk. Credit risk is the risk that a debt security could deteriorate in quality to such an extent that its rating is downgraded or its market value declines relative to comparable securities. Changes in actual or perceived creditworthiness may occur quickly. If the Fund holds securities that have been downgraded, or that default on payment, such Fund's performance could be negatively affected.

Default Risk. Default risk refers to the risk that a company that issues a debt security will be unable to fulfill its obligation to repay principal and interest. The lower a bond is rated, the greater its default risk. To the extent the Fund holds securities that have been downgraded, or that default on payment, its performance could be negatively affected.

Equity Securities Risk. Equity investments are subject to greater fluctuations in market value than other asset classes as a result of such factors as a company's business performance, investor perceptions, stock market trends and general economic conditions.

Foreign Securities Risk. There are special risks associated with investing in foreign securities that are not typically associated with investing in U.S. companies. These risks include fluctuations in the exchange rates of foreign currencies that may affect the U.S. dollar value of a security, and the possibility of substantial price volatility as a result of political and economic instability in the foreign country. Other risks of investing in foreign securities include: less public information about issuers of securities, different securities regulation, different accounting, auditing and financial reporting standards and less liquidity in foreign markets than in U.S. markets.

High Yield Fixed-Income Securities (Junk Bonds) Risk. Investment in junk bonds entails a greater risk than an investment in higher-rated securities. Although junk bonds typically pay higher interest rates than investment-grade bonds, there is a greater likelihood that the company issuing the junk bond will default on interest and principal payments. In the event of an issuer's bankruptcy, claims of other creditors may have priority over the claims of junk bond holders, leaving few or no assets to repay them. Junk bonds are also more sensitive to adverse economic changes or individual corporate developments than higher

Additional Information About Investment Strategies and Related Risks

quality bonds. During a period of adverse economic changes, including a period of rising interest rates, companies issuing junk bonds may be unable to make principal and interest payments.

Large-Capitalization Investing Risk. Large-capitalization stocks as a group could fall out of favor with the market, which may cause a Fund to underperform funds that focus on other types of stocks. In addition, larger, more established companies may be unable to respond quickly to new competitive challenges such as changes in technology and consumer preferences. Many larger companies also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

Market Maker Risk. If the Fund has lower average daily trading volumes, it may rely on a small number of third-party market makers to provide a market for the purchase and sale of Fund Shares. Any trading halt or other problem relating to the trading activity of these market makers could result in a dramatic change in the spread between the Fund's net asset value and the price at which the Fund Shares are trading on the Exchange, which could result in a decrease in value of the Fund Shares. In addition, decisions by market makers or authorized participants to reduce their role or step away from these activities in times of market stress could inhibit the effectiveness of the arbitrage process in maintaining the relationship between the underlying values of the Fund's portfolio securities and the Fund's market price. This reduced effectiveness could result in Fund Shares trading at a discount to net asset value and also in greater than normal intra-day bid-ask spreads for Fund Shares.

Market Risk. The risk that the securities markets will increase or decrease in value is considered market risk and applies to any security. If there is a general decline in the stock or fixed-income market, it is possible your investment may lose value regardless of the individual results of the companies in which the Fund invests.

National Closed Market Trading Risk. To the extent that the underlying securities and/or other assets held by the Fund trade on non-U.S. exchanges or in non-U.S. markets that may be closed when the securities exchange on which Fund Shares trade is open, there are likely to be deviations between the current price of such an underlying security and the last quoted price for the underlying security (i.e., the Fund's quote from the closed non-U.S. market). The impact of a closed foreign market on the Fund is likely to be greater where a large portion of the Fund's underlying securities and/or other assets trade on that closed non-U.S. market or when the non-U.S. market is closed for unscheduled reasons. These deviations could result in premiums or discounts to the Fund's NAV that may be greater than those experienced by other ETFs.

New Fund Risk. The Fund is a recently organized investment company with a limited operating history. As a result, prospective investors have a limited track record or history on which to base their investment decision.

Non-Diversification Risk. The Fund is classified as "non-diversified" under the 1940 Act. As a result, the Fund is only limited as to the percentage of its assets which may be invested in the securities of any one issuer by the diversification requirements imposed by the Internal Revenue Code of 1986, as amended. The Fund may invest a relatively high percentage of its assets in a limited number of issuers. As a result, the Fund may be more susceptible to a single adverse economic or regulatory occurrence affecting one or more of these issuers, experience increased volatility and be highly invested in certain issuers.

Options Risk. There are significant differences between the securities and options markets that could result in an imperfect correlation among these markets, causing a given transaction not to achieve its objectives. The Fund's ability to utilize options successfully will depend on Calamos Advisors' ability to predict pertinent market movements, which cannot be assured.

The Fund's ability to close out its position as a purchaser or seller of an Options Clearing Corporation or exchange-listed put or call option is dependent, in part, upon the liquidity of the options market. If the Fund were unable to close out an option that it had purchased on a security, it would have to exercise the option to realize any profit or the option would expire and become worthless. If the Fund were unable to close out a covered call option that it had written on a security, it would not be able to sell the underlying security until the option expired. As the writer of a covered call option on a security, the Fund foregoes, during the option's life, the opportunity to profit from increases in the market value of the security covering the call option above the sum of the premium and the exercise price of the call. The hours of trading for listed options may not coincide with the hours during which the underlying financial instruments are traded. To the extent that the option markets close before the markets for the underlying financial instruments, significant price and rate movements can take place in the underlying markets that cannot be reflected in the option markets until the next trading day.

Additional Information About Investment Strategies and Related Risks

Unless the parties provide for it, there is no central clearing or guaranty function in an over-the-counter option. As a result, if the counterparty fails to make or take delivery of the security or other instrument underlying an over-the-counter option it has entered into with the Fund or fails to make a cash settlement payment due in accordance with the terms of that option, the Fund will lose any premium it paid for the option as well as any anticipated benefit of the transaction. Accordingly, Calamos Advisors must assess the creditworthiness of each such counterparty or any guarantor or credit enhancement of the counterparty's credit to determine the likelihood that the terms of the over-the-counter option will be satisfied.

The Fund may also purchase or write over-the-counter put or call options, which involves risks different from, and possibly greater than, the risks associated with exchange-listed put or call options. In some instances, over-the-counter put or call options may expose the Fund to the risk that a counterparty may be unable or unwilling to perform according to a contract, and that any deterioration in a counterparty's creditworthiness could adversely affect the instrument. In addition, the Fund may be exposed to a risk that losses may exceed the amount originally invested.

Portfolio Selection Risk. The value of your investment may decrease if the judgment of Calamos Advisors about the attractiveness, value or market trends affecting a particular security, issuer, industry, or sector or about market movements is incorrect.

Portfolio Turnover Risk. Engaging in active and frequent trading of securities may result in a higher than average level of capital gains and greater transaction costs to the Fund, including brokerage commissions or dealer mark-ups and other transaction costs on the sale and reinvestments of securities. Such sales may also result in the realization of capital gains, including short-term capital gains (which are taxed at ordinary income tax rates for federal income tax purposes, rather than at lower capital gains rates) and may adversely impact the Fund's performance. It is possible that the Fund engaging in active and frequent trading may be required to make significant distributions derived from taxable gains, regardless of the Fund's net longer term performance. The trading costs and tax effects associated with portfolio turnover will adversely affect the Fund's performance and lower the Fund's effective return for investors.

Premium-Discount Risk. The Fund Shares may trade above or below their net asset value ("NAV"). The market prices of Fund Shares will generally fluctuate in accordance with changes in NAV as well as the relative supply of, and demand for, Fund Shares on the Exchange. The trading price of Fund Shares may deviate significantly from NAV during periods of market volatility.

Rule 144A Securities Risk. The Fund may invest in securities that are issued and sold through transactions under Rule 144A of the Securities Act of 1933. Under the supervision of its board of trustees, the Fund will determine whether Rule 144A Securities are illiquid. If qualified institutional buyers are unwilling to purchase these Rule 144A Securities, the percentage of the Fund's assets invested in illiquid securities would increase. Typically, the Fund purchases Rule 144A Securities if the Fund's adviser has determined them to be liquid. If any Rule 144A Security held by the Fund should become illiquid, the value of the security may be reduced and a sale of the security may be more difficult.

Secondary Market Trading Risk. Investors buying or selling Fund Shares in the secondary market will pay brokerage commissions or other charges imposed by brokers as determined by that broker. Brokerage commissions are often a fixed amount and may be a significant proportional cost for investors seeking to buy or sell relatively small amounts of Fund Shares. Although the Fund Shares are listed on the Exchange, there can be no assurance that an active or liquid trading market for them will develop or be maintained. In addition, trading in Fund Shares on the Exchange may be halted.

Sector Risk. To the extent the Fund invests a significant portion of its assets in a particular sector, a greater portion of the Fund's performance may be affected by the general business and economic conditions affecting that sector. Each sector may share economic risk with the broader market, however there may be economic risks specific to each sector. As a result, returns from those sectors may trail returns from the overall stock market and it is possible that the Fund may underperform the broader market, or experience greater volatility.

Securities Lending Risk. The Fund may lend its portfolio securities to broker-dealers and banks in order to generate additional income for the Fund. Any such loan must be continuously secured by collateral in cash or cash equivalents maintained on a current basis in an amount at least equal to the market value of the securities loaned by the Fund. In the event of bankruptcy

Additional Information About Investment Strategies and Related Risks

or other default of a borrower of portfolio securities, the Fund could experience both delays in liquidating the loan collateral or recovering the loaned securities and losses, including (a)possible decline in the value of the collateral or in the value of the securities loaned during the period while the Fund seeks to enforce its rights thereto, (b)possible subnormal levels of income and lack of access to income during this period, and (c)expenses of enforcing its rights. In an effort to reduce these risks, the Fund's securities lending agent monitors, and reports to Calamos Advisors on, the creditworthiness of the firms to which the Fund lends securities. The Fund may also experience losses as a result of a diminution in value of its cash collateral investments.

Small and Mid-Sized Company Risk. Small and mid-sized company stocks have historically been subject to greater investment risk than large company stocks. The risks generally associated with these companies include more limited product lines, markets and financial resources, lack of management depth or experience, dependency on key personnel, and vulnerability to adverse market and economic developments. Accordingly, the prices of mid-sized company stocks tend to be more volatile than prices of large company stocks. Further, the prices of small company stocks are often adversely affected by limited trading volumes and the lack of publicly available information.

Synthetic Convertible Instruments Risk. The value of a synthetic convertible instrument will respond differently to market fluctuations than a convertible security because a synthetic convertible instrument is composed of two or more separate securities, each with its own market value. In addition, if the value of the underlying common stock or the level of the index involved in the convertible component falls below the exercise price of the warrant or option, the warrant or option may lose all value.

Trading Issues Risk. Trading in Fund Shares on the Exchange may be halted due to market conditions or for reasons that, in the view of the Exchange, make trading in shares inadvisable. In addition, trading in Fund Shares on the Exchange is subject to trading halts caused by extraordinary market volatility pursuant to the Exchange's "circuit breaker" rules. There can be no assurance that the requirements of the Exchange necessary to maintain the listing of the Fund will continue to be met or will remain unchanged. The Fund may have difficulty maintaining its listing on the Exchange in the event the Fund's assets are small, the Fund does not have enough shareholders, or if the Fund is unable to proceed with creation and/or redemption orders.

The following are non-principal risks that generally apply to the Fund:

Cybersecurity Risk. Investment companies, such as the Fund, and their service providers are exposed to operational and information security risks resulting from cyberattacks, which may result in financial losses to the Fund and its shareholders. Cyber- attacks include, among other behaviors, stealing or corrupting data maintained online or digitally, denial of service attacks on websites, "ransomware" that renders systems inoperable until ransom is paid, the unauthorized release of confidential information, or various other forms of cybersecurity breaches. Cyber-attacks affecting the Fund, Calamos Advisors, custodian, transfer agent, distributor, administrator, intermediaries, trading counterparties, and other third-party service providers may adversely impact the Fund or the companies in which the Fund invests, causing the Fund's investments to lose value or to prevent a shareholder redemption or purchase from clearing in a timely manner.

Inflation Risk. The risk that the value of assets or income from the Fund's investments will be worth less in the future as inflation decreases the value of payments at future dates is considered inflation risk. As inflation increases, the value of the Fund's portfolio could decline. Inflation rates may change frequently and drastically as a result of various factors and the Fund's investments may not keep pace with inflation, which may result in losses to the Fund's investors or adversely affect the value of shareholders' investments in the Fund.

Investment Management Risk. Whether the Fund achieves its investment objective(s) is significantly impacted by whether Calamos Advisors is able to choose suitable investments for the Fund.

Market Disruption Risk. Certain events have a disruptive effect on securities markets, including but not limited to, terrorist attacks, war and other geopolitical events or catastrophes. Calamos Advisors cannot predict the effect of similar events in the future on the U.S. or foreign economies. Certain securities such as high yield and equity securities tend to be impacted more by these events than other types of securities in terms of price and volatility.

Additional Information About Investment Strategies and Related Risks

Operational Risk. The Fund is subject to risks arising from various operational factors, including, but not limited to, human error, processing and communication errors, errors of the Fund's service providers, counterparties or other third-parties, failed or inadequate processes and technology or systems failures. The Fund relies on third-parties for a range of services, including custody. Any delay or failure relating to engaging or maintaining such service providers may affect the Fund's ability to meet its investment objective. Although the Fund and the Adviser seek to reduce these operational risks through controls and procedures, there is no way to completely protect against such risks.

Recent Market Events. Since the 2008 financial crises, financial markets throughout the world have experienced periods of increased volatility, depressed valuations, decreased liquidity and heightened uncertainty and turmoil. This turmoil resulted in unusual and extreme volatility in the equity and debt markets, in the prices of individual securities and in the world economy. Events that have contributed to these market conditions include, but are not limited to, major cybersecurity events, geopolitical events (including wars, terror attacks, and public health emergencies), measures to address budget deficits, downgrading of sovereign debt, dramatic changes in currency exchange rates, and public sentiment.

In addition, policy and legislative changes in the United States and in other countries are changing many aspects of financial regulation. The impact of these changes on the markets, and the practical implications for market participants, may not be fully known for some time. Widespread disease and virus epidemics, such as the coronavirus outbreak, could likewise be highly disruptive, adversely affecting individual companies, sectors, industries, markets, currencies, interest and inflation rates, credit ratings, investor sentiment, and other factors affecting the value of the Fund's investments.

Portfolio security holdings disclosure

A description of the Fund's policies and procedures in connection with the disclosure of portfolio security holdings of the Fund is available in the Fund's SAI at www.calamos.com.

Fund Facts

Who manages the Fund?

Investment Adviser

The Fund is advised by Calamos Advisors LLC ("Calamos Advisors" or the "Adviser"), 2020 Calamos Court, Naperville, Illinois 60563. Calamos Advisors, an investment adviser registered with the SEC effective May 29, 1987, is a wholly owned subsidiary of Calamos Investments LLC ("CILLC"). CILLC's assets under management as of December 31, 2023, were $35 billion ($34 billion of which represented Calamos Advisors' assets under management). Calamos Asset Management, Inc. ("CAM") is the sole manager of CILLC. As of December 31, 2023, approximately 22% of the outstanding interests of CILLC was owned by CAM and the remaining approximately 78% of CILLC was owned by Calamos Partners LLC ("CPL") and John P. Calamos, Sr. CAM was owned by John P. Calamos, Sr. and John S. Koudounis, and CPL was owned by John S. Koudounis and Calamos Family Partners, Inc. ("CFP"). CFP was beneficially owned by members of the Calamos family, including John P. Calamos, Sr.

Subject to the overall authority of the Board of Trustees, Calamos Advisors provides continuous investment supervision and management to the Fund under a management agreement and also furnishes office space, equipment and management personnel. For these services, the Fund pays Calamos Advisors a fee based on its average daily net assets, which is accrued daily and paid on a monthly basis. The Fund will pay fees (before any reimbursement) under the management agreement in the following amounts as a percentage of its average net assets:

Out of this management fee, Calamos Advisors pays substantially all expenses of the Fund, including the cost of transfer agency, custody, fund administration, legal, audit and other service and license fees, except for distribution and service fees payable pursuant to a Rule 12b-1 plan, if any, acquired fund fees and expenses, brokerage commissions and other expenses connected with the execution of portfolio transactions, taxes, interest, and extraordinary expenses.

At a meeting held on September 1, 2023, the Board of Trustees approved the Investment Management Agreement for the Fund. A discussion regarding the basis for the Board's approval of the Investment Management Agreement on behalf of the Fund is included in the Fund's Form N-CSR for the fiscal year ended July 31, 2024.

Portfolio Managers

John Hillenbrand. John Hillenbrand joined Calamos Advisors in 2002 and since September 2015 is a Co-CIO, Head of Multi-Asset Strategies and Co-Head of Convertible Strategies, as well as a Senior Co-Portfolio Manager. From March 2013 to September 2015 he was a Co-Portfolio Manager. Between August 2002 and March 2013 he was a senior strategy analyst.

Joe Wysocki. Joe Wysocki joined Calamos Advisors in October 2003 and since February 2021 is a Senior Co-Portfolio Manager. Previously, he was a Co-Portfolio Manager from March 2015 to February 2021; a sector head from March 2014 to March 2015; a Co-Portfolio Manager from March 2013 to March 2014; and a senior strategy analyst from February 2007 and March 2013.

Jon Vacko. Jon Vacko joined Calamos Advisors in 2000 and has been a Senior Co-Portfolio Manager since September 2015. Previously, he was a Co-Portfolio Manager from August 2013 to September 2015; prior thereto he was a Co-Head of Research and Investments from July 2010 to August 2013.

The Fund's SAI provides additional information about each portfolio manager, including other accounts they manage, their ownership in the Calamos Family of Funds and their compensation.

Management Approach

Calamos Advisors employs a "team of teams" approach to portfolio management, led by the Global CIO and our CIO team consisting of 5 Co-CIOs with specialized areas of investment expertise. The Global CIO and Co-CIO team are responsible for oversight of investment team resources, investment processes, performance and risk. As heads of investment verticals, Co-CIOs manage investment team members and, along with Co- Portfolio Managers and Associate Portfolio Managers, have day-to-day

Fund Facts

portfolio oversight and construction responsibilities of their respective investment strategies. While investment research professionals within each Co-CIO's team are assigned specific strategy responsibilities, they also provide support to other investment team verticals, creating deeper insights across a wider range of investment strategies. The combination of specialized investment teams with cross team collaboration results in what we call our team of teams approach.

This team of teams approach is further reflected in the composition of Calamos Advisors' Investment Committee, made up of the Global CIO, the Co-CIO team, and the Global Head of Trading. Other members of the investment team participate in Investment Committee meetings in connection with specific investment related issues or topics as deemed appropriate.

The structure and composition of the Investment Committee results in a number of benefits, as it:

•  Leads to broader perspective on investment decisions: multiple viewpoints and areas of expertise feed into consensus;

•  Promotes collaboration between teams; and

•  Functions as a think tank with the goal of identifying ways to outperform the market on a risk-adjusted basis.

The objectives of the Investment Committee are to:

•  Form the firm's top-down macro view, market direction, asset allocation, and sector/country positioning.

•  Establish firm-wide secular and cyclical themes for review.

•  Review firm-wide and portfolio risk metrics, recommending changes where appropriate.

•  Review firm-wide, portfolio and individual security liquidity constraints.

•  Evaluate firm-wide and portfolio investment performance.

•  Evaluate firm-wide and portfolio hedging policies and execution.

•  Evaluate enhancements to the overall investment process.

John Hillenbrand, Jon Vacko, and Joe Wysocki are each Senior Co-Portfolio Managers of the Fund. Senior Co- Portfolio Managers are collectively referred to within this registration statement as "Portfolio Managers".

How to Buy and Sell Shares

Fund Shares are listed for secondary trading on the Exchange under the symbol CVRT and individual Fund Shares may only be purchased and sold in the secondary market through a broker-dealer. The Exchange and secondary markets are closed on weekends and also are generally closed on the following holidays: New Year's Day, Dr. Martin Luther King, Jr. Day, Presidents' Day, Good Friday, Memorial Day (observed), Juneteenth, Independence Day, Labor Day, Thanksgiving Day and Christmas Day. The Exchange may close early on the business day before certain holidays and on the day after Thanksgiving Day. Exchange holiday schedules are subject to change without notice. If you buy or sell Fund Shares in the secondary market, you will pay the secondary market price for Fund Shares. In addition, you may incur customary brokerage commissions and charges and may pay some or all of the spread between the bid and the offered price in the secondary market on each leg of a round trip (purchase and sale) transaction.

The trading prices of Fund Shares will fluctuate continuously throughout trading hours based on market supply and demand rather than the relevant Fund's net asset value, which is calculated at the end of each business day. Fund Shares will trade on the Exchange at prices that may be above (i.e., at a premium) or below (i.e., at a discount), to varying degrees, the daily net asset value of Fund Shares. The trading prices of Fund Shares may deviate significantly from the Fund's net asset value during periods of market volatility. Given, however, that Fund Shares can be issued and redeemed daily in Creation Units, the Adviser believes that large discounts and premiums to net asset value should not be sustained over long periods.

Authorized Participants may acquire shares directly from the Fund, and Authorized Participants may tender their shares for redemption directly to the Fund, at NAV per share only in Creation Units. Purchases and redemptions directly with the Fund must follow the Fund's procedures, which are described in the SAI.

The Fund may liquidate and terminate at any time without shareholder approval.

Fund Facts

Book Entry

Fund Shares are held in book-entry form, which means that no stock certificates are issued. The Depository Trust Company ("DTC") or its nominee is the record owner of all outstanding Shares of the Fund and is recognized as the owner of all Shares for all purposes.

Investors owning Fund Shares are beneficial owners as shown on the records of DTC or its participants. DTC serves as the securities depository for all Fund Shares. Participants in DTC include securities brokers and dealers, banks, trust companies, clearing corporations and other institutions that directly or indirectly maintain a custodial relationship with DTC. As a beneficial owner of Fund Shares, you are not entitled to receive physical delivery of stock certificates or to have Fund Shares registered in your name, and you are not considered a registered owner of Fund Shares. Therefore, to exercise any right as an owner of Fund Shares, you must rely upon the procedures of DTC and its participants. These procedures are the same as those that apply to any other securities that you hold in book entry or "street name" form.

Fund Share Trading Prices

The trading prices of Shares of the Fund on the Exchange may differ from the Fund's daily NAV. Market forces of supply and demand, economic conditions and other factors may affect the trading prices of Shares of the Fund.

The approximate value of Shares of the Fund, an amount representing on a per share basis the sum of the current market price of the cash or securities, as applicable, accepted by the Fund in exchange for Shares of the Fund and an estimated cash component, if any, is disseminated every 15 seconds throughout the trading day through the facilities of the Consolidated Tape Association. This approximate value should not be viewed as a "real-time" update of the NAV per Share of the Fund because the approximate value may not be calculated in the same manner as the NAV, which is computed once a day, generally at the end of the business day. The Fund is not involved in, or responsible for, the calculation or dissemination of the approximate value of the Fund Shares and the Fund does not make any warranty as to its accuracy.

Frequent Purchases and Redemptions of Fund Shares

Shares of the Fund may be purchased and redeemed directly from the Fund only in Creation Units by Authorize Participants. The vast majority of trading in Shares of the Fund occurs on the secondary market, and does not involve the Fund directly. In-kind purchases and redemptions of Creation Units by Authorized Participants and cash trades on the secondary market are unlikely to cause many of the harmful effects of frequent purchases and/or redemptions of Fund Shares. Cash purchases and/or redemptions of Creation Units, however, can result in disruption of portfolio management, dilution to the Fund and increased transaction costs, which could negatively impact the Fund's ability to achieve its investment objective, and may lead to the realization of capital gains. These consequences may increase as the frequency of cash purchases and redemptions of Creation Units by Authorized Participants increases. However, direct trading by Authorized Participants is critical to ensuring that Fund Shares trade at or close to NAV.

The Fund imposes no restrictions on the frequency of purchases and redemptions ("market timing"). To minimize these potential consequences of frequent purchases and redemptions of Fund Shares, the Fund employs fair valuation pricing, and imposes transaction fees on purchases and redemptions of Creation Units to cover the custodial and other costs the Fund incurs in effecting trades. In addition, the Adviser monitors trades by Authorized Participants for patterns of abusive trading and the Fund reserves the right to not accept orders from Authorized Participants that the Adviser has determined may be disruptive to the management of the Fund, or otherwise are not in the best interests of the Fund. For these reasons, the Board has not adopted policies and procedures with respect to frequent purchases and redemptions of Fund Shares. The Trust's policies and procedures regarding frequent purchases and redemptions may be modified by the Board of Trustees at any time.

The Trust's policies and procedures prohibit the practice of any officer or employee of the Trust, a Trust investment adviser (including any sub-adviser), the distributor, custodian, or transfer agent, or other affiliated person of the Trust placing orders to purchase or redeem shares of a series of the Trust after the designated time as of which the Fund calculates its NAV (i.e. "late trading").

Fund Facts

Distribution and Service Plan

The Fund has adopted a distribution and service plan ("Plan") pursuant to Rule 12b-1 under the Investment Company Act. Under the Plan, the Fund is authorized to pay distribution fees to the Distributor and other firms that provide distribution and shareholder services ("Service Providers"). If a Service Provider provides such services, the Fund may pay fees at an annual rate not to exceed 0.25% of average daily net assets, pursuant to Rule 12b-1 under the Investment Company Act.

No distribution or service fees are currently paid by the Fund, however, and there are no current plans to impose these fees. In the event Rule 12b-1 fees are charged, over time they would increase the cost of an investment in the Fund because they would be paid on an ongoing basis.

Fund Website and Disclosure of Portfolio Holdings

The Trust maintains a website for the Fund at www.calamos.com. Among other things, this website includes this Prospectus and the SAI, and will include the Fund's holdings, the Fund's last annual and semi-annual reports (when available), pricing information about Fund Shares trading on the Exchange, daily NAV calculations and a historical comparison of the trading prices to NAV.

Each day the Fund is open for business, the Trust publicly disseminates the Fund's full portfolio holdings as of the close of the previous day through its website at www.calamos.com. A description of the Trust's policies and procedures with respect to the disclosure of the Fund's portfolio holdings is available in the Fund's SAI.

Dividends, Other Distributions and Taxes

Fund Distributions

The Fund generally pays out dividends from its net investment income, if any, to shareholders monthly, and distributes its net capital gains, if any, to shareholders annually. The Fund typically earns dividends from stocks in which it invests. These amounts, net of expenses, are passed along to Fund shareholders as "income dividends." The Fund realizes capital gains or losses whenever it sells securities. Net long-term capital gains are distributed to shareholders as "capital gain dividends."

Brokers may make available to their customers who own Fund Shares the DTC book-entry dividend reinvestment service. To determine whether the dividend reinvestment service is available and whether there is a commission or other charge for using this service, consult your broker. Brokers may require Fund shareholders to adhere to specific procedures and timetables. If this service is available and used, dividend distributions of both income and net realized gains will be automatically reinvested in additional whole Fund Shares of the Fund purchased in the secondary market. Without this service, investors would receive their distributions in cash.

Taxes

As with any investment, you should consider how your investment in Fund Shares will be taxed. The tax information in this prospectus is provided only as general information. This section is current as of the date of this prospectus. Tax laws and interpretations change frequently, and these summaries do not describe all of the tax consequences to all taxpayers. For example, these summaries generally do not describe your situation if you are a corporation, a non-U.S. person, a broker-dealer, or other investor with special circumstances. However, with respect to certain tax issues, the summaries describe the general tax treatment of certain distributions made to corporations and non-U.S. persons. In addition, this section does not describe your state, local or non-U.S. tax consequences. You should consult your own tax advisor about the tax consequences of an investment in Fund Shares.

Fund distributions to you and the sale or redemption of your Fund Shares will have tax consequences to you. Such consequences may be different if you hold your Shares through a tax-exempt entity or tax-advantaged retirement account, such as an individual retirement account or 401(k) plan.

The Fund intends to elect to be treated, and intends to qualify each year, as a regulated investment company (a "RIC") under the Internal Revenue Code of 1986, as amended (the "Code"). As a RIC, the Fund is generally not subject to corporate-level U.S. federal income tax on any net ordinary income or capital gains that are timely distributed to shareholders. However, the Fund's failure to qualify as a RIC or to meet minimum distribution requirements would result (if certain relief provisions were not available) in corporate-level taxation and, consequently, a reduction in amounts available for distribution to shareholders.

Fund Facts

Taxes on Distributions

Distributions by the Fund generally are taxable to you as ordinary income or capital gains. Distributions are subject to federal income tax, whether received in cash or reinvested in additional Fund Shares or shares of another fund, and may be subject to state or local taxes. Distributions of the Fund's "investment company taxable income" generally will be taxable as ordinary income to the extent of the Fund's current or accumulated earnings and profits. Notwithstanding the foregoing, distributions that are attributable to "qualified dividends" received by the Fund may be eligible to be taxed at long-term capital gains rates, as long as the Fund and the shareholder meet certain holding period requirements.

Distributions of the Fund's net capital gain that are properly reported by the Fund as "capital gain dividends" will generally be taxable to you as long-term capital gains, currently at a maximum rate of 20%, regardless of your holding period in the Fund's Shares. Distributions in excess of the Fund's current and accumulated earnings and profits first will reduce your adjusted tax basis in your Fund Shares and, after the adjusted basis is reduced to zero, will constitute capital gain. Such capital gain will be long-term capital gain and thus, will be taxed at a maximum rate of 20%, if the distributions are attributable to Fund Shares that you have held for more than one year.

Certain non-corporate taxpayers will also be subject to a 3.8% U.S. federal Medicare contribution tax with respect to the lesser of (1) their "net investment income" or (2) the excess of their "modified adjusted gross income" over a threshold amount ($200,000 for single taxpayers and $250,000 for taxpayers who are married and filing jointly).

Corporate shareholders of the Fund are generally eligible for a dividends-received deduction with respect to ordinary income dividends (but not capital gain dividends) properly designated as eligible for such deduction by the Fund, as long as the Fund and the corporate shareholder meet certain holding period and other requirements.

Under a dividend reinvestment service, you may have the option to have all cash distributions automatically reinvested in additional Fund Shares. Any distributions reinvested under such a service will nevertheless be taxable to you as described above.

You will have an adjusted basis in the additional Fund Shares purchased through such a reinvestment service equal to the amount of the reinvested distribution plus the amount of any fees charged for the transaction. The additional Fund Shares will have a holding period commencing on the day following the day on which they are credited to your account.

A distribution will reduce the Fund's NAV per Share and generally will be taxable to you as ordinary income or capital gain even if it is paid from income or gains earned by the Fund before you invested in the Fund and thus, from an investment standpoint, constitutes a return of capital. In general, distributions are subject to federal income tax as of the date of payment. However, distributions paid in January will be treated as paid on December 31 of the prior year if they were declared and payable to shareholders of record on a date in October, November or December of the prior year.

The Fund's investments in certain debt instruments could cause the Fund to recognize taxable income in excess of the cash generated by such investments, which may require the Fund to dispose of other investments in order to make required distributions.

The Fund's transactions in derivatives, as well as any of its hedging, short sale, securities loan or similar transactions may be subject to one or more special tax rules. These rules may affect whether gains and losses recognized by the Fund are treated as ordinary or capital, accelerate the recognition of income or gains to the Fund, defer losses to the Fund, and cause adjustments in the holding periods of the Fund's securities, thereby affecting whether capital gains and losses are treated as short-term or long-term. These rules could therefore affect the amount, timing and/or character of distributions to shareholders and thus taxes payable by shareholders.

You may be subject to federal back-up withholding tax, if you do not provide the Fund with a taxpayer identification number (for an individual, a social security number) and make other required certifications, or the Internal Revenue Service informs the Fund that your tax identification number is incorrect. Backup withholding is not an additional tax. You may claim the amount withheld as a credit on your federal income tax return, provided you furnish the appropriate information to the Internal Revenue Service.

Fund Facts

Taxes When Shares are Sold

Any capital gain or loss realized upon a sale of Fund Shares is generally treated as long-term capital gain or loss if you have held the Fund Shares for more than one year and as short-term capital gain or loss if you have held the Fund Shares for one year or less. The ability to deduct capital losses realized on a sale of Fund Shares may be limited.

Taxes on Purchase and Redemption of Creation Units

An Authorized Participant that exchanges equity securities for Creation Units will generally recognize a gain or a loss on the exchange. Any such gain or loss will be equal to the difference between the market value of the Creation Units at the time of the exchange, plus (or minus) the cash amount received (or paid), and such Authorized Participant's aggregate basis in the securities surrendered. A person who redeems Creation Units for equity securities will generally recognize a gain or loss equal to the difference between the aggregate market value of the securities received, plus (or minus) any cash received (or paid), and such person's basis in the Creation Units redeemed. The Internal Revenue Service, however, may assert that a loss realized upon an exchange of securities for Creation Units cannot be deducted currently under the rules governing "wash sales," or on the basis that there has been no significant change in the Authorized Participant's economic position with respect to such Creation Units. Persons exchanging securities should consult their own tax advisor with respect to the applicability of the wash sale rules and the availability and timing of a deduction for any loss. In addition, when a regulated investment company redeems a shareholder in kind, the regulated investment company generally is not required to recognize taxable gains in respect of the portfolio securities it distributes to the redeeming shareholder. However, the Fund may be required to recognize taxable gain on the distribution of certain securities, and the Internal Revenue Service may assert that the Fund must recognize taxable gain in respect of certain other securities that the Fund distributes to a shareholder in exchange for Creation Units, which may increase the amount of taxable gains that the Fund would otherwise be required to distribute in order to maintain its qualification as a regulated investment company and avoid a Fund-level tax.

Any capital gain or loss realized upon a redemption of Creation Units is generally treated as long-term capital gain or loss if the Creation Units have been held for more than one year and as short-term capital gain or loss if the Creation Units have been held for one year or less. If you purchase or redeem Creation Units, you will be sent a confirmation statement showing how many Fund Shares you purchased or sold and at what price.

Authorized Participants that are dealers may be subject to special tax rules and should consult their own tax advisors regarding the tax consequences of purchasing and redeeming Creation Units in their capacity as dealers.

Treatment of Fund Expenses

Expenses incurred and deducted by the Fund will generally not be treated as income taxable to you.

Non-U.S. Taxes

Income and proceeds received by the Fund from sources within foreign countries may be subject to withholding and other taxes imposed by such countries, which would reduce the Fund's return on investments in such countries. Tax treaties between certain countries and the U.S. may reduce or eliminate such taxes. Shareholders generally will not be entitled separately to claim a credit or deduction in respect of non-U.S. taxes paid or treated as paid by the Fund. In addition, the Fund's investments in foreign securities or foreign currencies may increase or accelerate the Fund's recognition of ordinary income and may affect the timing or amount of the Fund's distributions.

Non-U.S. Investors

If you are a non-U.S. investor (i.e., an investor other than a U.S. citizen or resident or a U.S. corporation, partnership, estate or trust), you should be aware that, generally, subject to applicable tax treaties, distributions from the Fund will be characterized as dividends for U.S. federal income tax purposes (other than dividends which the Fund properly reports as capital gain dividends) and will be subject to U.S. federal income taxes, including withholding taxes, subject to certain exceptions described below. However, distributions received by a non-U.S. investor from the Fund that are properly reported by the Fund as capital gain dividends may not be subject to U.S. federal income taxes, including withholding taxes, provided that the Fund makes certain elections and certain other conditions are met. Distributions from the Fund that are properly reported by the Fund as an interest-related dividend attributable to certain interest income received by the Fund or as a short-term capital gain dividend attributable to certain net short-term capital gain income received by the Fund may not be subject to U.S. federal income taxes,

Fund Facts

including withholding taxes when received by certain non-U.S. investors, provided that the Fund makes certain elections and certain other conditions are met.

Distributions may be subject to a U.S. withholding tax of 30% in the case of distributions to (i) certain non-U.S. financial institutions that have not entered into an agreement with the U.S. Treasury to collect and disclose certain information and are not resident in a jurisdiction that has entered into such an agreement with the U.S. Treasury and (ii) certain other non-U.S. entities that do not provide certain certifications and information about the entity's U.S. owners. The Internal Revenue Service and the Department of Treasury have issued proposed regulations providing that these withholding rules will not be applicable to the gross proceeds of share redemptions or capital gains dividends that the Fund pays.

Investments in Certain Non-U.S. Corporations

If the Fund holds an equity interest in any "passive foreign investment companies" ("PFICs"), which are generally certain non-U.S. corporations that receive at least 75% of their annual gross income from passive sources (such as interest, dividends, certain rents and royalties or capital gains) or that hold at least 50% of their assets in investments producing such passive income, the Fund could be subject to U.S. federal income tax and additional interest charges on gains and certain distributions with respect to those equity interests, even if all the income or gain is timely distributed to its shareholders. The Fund will not be able to pass through to its shareholders any credit or deduction for such taxes. The Fund may be able to make an election that could ameliorate these adverse tax consequences. For instance, the Fund may elect to mark the gains (and to a limited extent losses) in such holdings "to the market" as though it had sold (and, solely for purposes of this mark-to-market election, repurchased) its holdings in those PFICs on the last day of the Fund's taxable year. If the Fund were to make a mark-to-market election, it would recognize as ordinary income any increase in the value of such PFIC shares, and as ordinary loss any decrease in such value to the extent it did not exceed prior increases included in income. Under this election, the Fund might be required to recognize in a year income in excess of its distributions from PFICs and its proceeds from dispositions of PFIC stock during that year, and such income would nevertheless be subject to the distribution requirement and would be taken into account for purposes of the 4% excise tax that may be imposed on the undistributed income of a RIC. Dividends paid by PFICs are not treated as qualified dividend income.

Other Tax Matters

The foregoing is only a summary of certain federal income tax considerations of investing in the Fund under current law, which is subject to change in the future. Shareholders who are not U.S. persons within the meaning of the Code, such as non-resident aliens, foreign trusts or estates, or foreign corporations or partnerships may be subject to different U.S. federal income tax treatment.

You may also be subject to state and local taxes on distributions paid by the Fund, and sales and redemptions of Fund Shares. You should consult your tax advisor for further information regarding federal, state, local and/or foreign tax consequences relevant to your specific tax situation. More information about taxes can be found in the Fund's SAI.

Net Asset Value

The NAV of shares is determined at the close of regular trading on the New York Stock Exchange (normally 4:00 p.m. Eastern Time) on each day the New York Stock Exchange ("NYSE") is open. NAV is computed by determining the aggregate market value of all assets of the Fund, less its liabilities, divided by the total number of shares outstanding ((assets-liabilities)/number of shares = NAV). The NYSE is closed on weekends and New Year's Day, Martin Luther King, Jr. Day, Presidents' Day, Good Friday, Memorial Day, Juneteenth National Independence Day, Independence Day, Labor Day, Thanksgiving Day and Christmas Day. The NAV takes into account the expenses and fees of the Fund, including management fees, which are accrued daily. The determination of NAV for the Fund for a particular day is applicable to all applications for the purchase of shares, as well as all requests for the redemption of shares, received by the Fund (or an authorized broker or agent, or its authorized designee) before the close of trading on the NYSE on that day.

Generally, securities traded or dealt in upon one or more securities exchanges (whether domestic or foreign) for which market quotations are readily available and not subject to restrictions against resale shall be valued at the last quoted sales price on the primary exchange or, in the absence of a sale on the primary exchange, at the mean between the current bid and ask prices on such exchange. Securities primarily traded in the National Association of Securities Dealers' Automated Quotation System

Fund Facts

("NASDAQ") National Market System for which market quotations are readily available shall be valued using the NASDAQ official closing price. Securities that are not traded or dealt in any securities exchange (whether domestic or foreign) and for which over-the-counter market quotations are readily available generally shall be valued at the last sale price or, in the absence of a sale, at the mean between the current bid and ask price on such over-the-counter market. Debt securities not traded on an exchange may be valued at prices supplied by a pricing agent (s) based on broker or dealer supplied valuations or matrix pricing, a method of valuing securities by reference to the value of other securities with similar characteristics, such as rating, interest rate and maturity. Futures, swaps and options contracts listed for trading on a futures or options exchange or board of trade for which market quotations are generally available are valued at the last quoted sale price, or, in the absence of a sale, at the mean of the last bid and ask price. Total return swaps on exchange-listed securities are valued at the last quoted sale price, or, in the absence of a sale, at the mean of the last bid and ask price.

Securities held by the Fund are valued in accordance with policies and procedures established by the Adviser pursuant to Rule 2a-5 under the Investment Company Act of 1940 ("1940 Act") and approved by and subject to the oversight of the Board of Trustees ("Valuation Procedures"). If market quotations are not readily available, securities or other assets will be valued at their fair value as determined in good faith by the Adviser in accordance with procedures approved by the Board and evaluated by the Board as to the reliability of the fair value method used. In these cases, the Fund's NAV will reflect certain portfolio securities' fair values rather than their market prices. Fair value pricing involves subjective judgments, and it is possible that the fair value determined for a security or other asset may be materially different than the value that could be realized upon the sale of that security or other asset. The fair value prices can differ from market prices. The Board of Trustees has designated Calamos Advisors as "valuation designee" for the Fund. The valuation designee is responsible for determining the value of the Fund's investments. The designee may also enlist third party consultants such as an audit firm or financial officer of a security issuer on an as-needed basis to assist in determining a security-specific fair value. The Board reviews and ratifies the execution of this process and the resultant fair value prices at least quarterly to assure the process produces reliable results.

The Fund may use independent pricing services to assist in calculating the value of the Fund's securities or other assets.

With respect to any portion of the Fund's assets that are invested in one or more open-end management investment companies registered under the 1940 Act, the Fund's net asset value is calculated based upon the net asset values of those open-end management investment companies, and the prospectuses for these companies explain the circumstances under which those companies will use fair value pricing and the effects of using fair value pricing.

Fund Service Providers

State Street Bank and Trust Company ("State Street"), located at One Congress Street, Suite 1, Boston, Massachusetts 02114-2016, serves as the Fund's administrator, custodian, fund accounting and financial accounting agent, and transfer agent.

Calamos Financial Services LLC ("CFS"), located at 2020 Calamos Court, Naperville, Illinois 60563, serves as the distributor of Creation Units for the Fund on an agency basis. The Distributor does not maintain a secondary market in Fund Shares.

Ropes & Gray LLP, located at 191 North Wacker Drive, 32^nd​ Floor, Chicago, IL 60606, serves as legal counsel to the Trust.

Premium/Discount Information

Information showing the number of days the market price of the Fund Shares was greater (at a premium) and less (at a discount) than the Fund's NAV for the most recently completed calendar year, and the most recently completed calendar quarters since that year (or the life of the Fund, if shorter), is available at www.calamos.com.

Investments by Other Investment Companies

Section 12(d)(1) of the 1940 Act restricts investments by investment companies in the securities of other investment companies, including Fund Shares. The SEC adopted Rule 12d1-4 under the 1940 Act on November 19, 2020, which became effective January 19, 2021. The Fund is required to comply with the conditions of Rule 12d1-4, which allows, subject to certain conditions, the Fund to invest in other registered investment companies and other registered investment companies to invest in the Fund beyond the limits contained in Section 12(d)(1) of the 1940 Act.

Financial Highlights

The financial highlights table is intended to help you understand the Fund's financial performance for the period of October 4, 2023 (commencement of operations) through July 31, 2024. Certain information reflects financial results for a single Fund share. The total returns in the table represent the rate that an investor would have earned (or lost) on an investment in the Fund (assuming reinvestment of all dividends and distributions). This information has been audited by Deloitte & Touche LLP, whose report, along with the Fund's financial statements, are included in the SAI, which is available upon request.

FINANCIAL HIGHLIGHTS

Selected data for a share outstanding throughout the period was as follows:

  •  Commencement of operations.

  (a)  Net investment income (loss) allocated based on average shares method.

  (b)  Distribution for annual periods determined in accordance with federal income tax regulations.

  (c)  Total return measures net investment income (loss) and capital gain or loss from portfolio investments assuming reinvestment of dividends and capital gains distributions. Total return is not annualized for periods that are less than a full year and does not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

  (d)  Annualized.

  (e)  Not annualized.

  (f)  Portfolio turnover rate excludes securities received or delivered from in-kind processing of creations or redemptions.

Other Information

Continuous Offering

The method by which Creation Units of Fund Shares are created and traded may raise certain issues under applicable securities laws. Because new Creation Units of Fund Shares are issued and sold by the Fund on an ongoing basis, a "distribution," as such term is used in the Securities Act of 1933, as amended (the "Securities Act"), may occur at any point. Broker-dealers and other persons are cautioned that some activities on their part may, depending on the circumstances, result in their being deemed participants in a distribution in a manner which could render them statutory underwriters and subject them to the prospectus delivery requirements and liability provisions of the Securities Act. For example, a broker-dealer firm or its client may be deemed a statutory underwriter if it takes Creation Units after placing an order with the Distributor, breaks them down into constituent Fund Shares and sells the Fund Shares directly to customers or if it chooses to couple the creation of a supply of new Fund Shares with an active selling effort involving solicitation of secondary market demand for Fund Shares. A determination of whether one is an underwriter for purposes of the Securities Act must take into account all the facts and circumstances pertaining to the activities of the broker-dealer or its client in the particular case, and the examples mentioned above should not be considered a complete description of all the activities that could lead to a characterization as an underwriter.

Broker-dealer firms should also note that dealers who are not "underwriters" but are effecting transactions in Fund Shares, whether or not participating in the distribution of Fund Shares, are generally required to deliver a prospectus. This is because the prospectus delivery exemption in Section 4(3) of the Securities Act is not available in respect of such transactions as a result of Section 24(d) of the Investment Company Act of 1940, as amended (the "Investment Company Act"). As a result, broker-dealer firms should note that dealers who are not "underwriters" but are participating in a distribution (as contrasted with engaging in ordinary secondary market transactions) and thus dealing with the Fund Shares that are part of an overallotment within the meaning of Section 4(3)(C) of the Securities Act, will be unable to take advantage of the prospectus delivery exemption provided by Section 4(3) of the Securities Act. For delivery of prospectuses to exchange members, the prospectus delivery mechanism of Rule 153 under the Securities Act is only available with respect to transactions on a national exchange.

Summary of Certain Provisions of the Second Amended and Restated Trust Instrument

The summary below is a synopsis of certain provisions contained in the Trust's Second Amended and Restated Trust Instrument (the "Trust Instrument"). Shareholders should refer to the Trust Instrument for further information. Defined terms have the meanings contained in the Trust Instrument.

Derivative Actions

The Second Amended and Restated Trust Instrument (the "Trust Instrument") requires, within Section 9 of Article IV, that before bringing any derivative action on behalf of the Fund, Shareholders must have made a written demand to the Board of Trustees requesting that they cause the Trust or affected Series or Class, as applicable, to file the action itself.

In order to warrant consideration, any such written demand must include at least the following:

(1)  a detailed description of the action or failure to act complained of and the facts upon which each such allegation is made;

(2)  a statement to the effect that the complaining Shareholders believe that they will fairly and adequately represent the interests of similarly situated Shareholders in enforcing the right of the Trust or the affected Series or Class, as applicable and an explanation of why the complaining Shareholders believe that to be the case;

(3)  a certification that the following requirements have been met, as well as information reasonably designed to allow the Trustees to verify that certification:

(a)  each complaining Shareholder was a Shareholder of the Trust or the affected Series or Class, as applicable, at the time of the action or failure to act complained of, or acquired the Shares afterwards by operation of law from a Person who was a Shareholder at that time; and

(b)  each complaining Shareholder was a Shareholder of the Trust or the affected Series or Class, as applicable, as of the time the demand required by Section 9 of Article IV was made; and

Other Information

(4)  a certification that each complaining Shareholder will be a Shareholder of the Trust or the affected Series or Class, as applicable as of the commencement of the derivative action.

The Trust Instrument further provides that at least 10% of the Shareholders of the Trust or the affected Series or Class, as applicable, must join in bringing the derivative action. This provision does not apply to claims brought under the federal securities laws.

The Trust Instrument also provides that a copy of the derivative complaint must be served on the Trust, assuming the requirements described above have already been met and the derivative action has not been barred as further described in the Trust Instrument.

Forum and Waiver of Jury Trial

Section 10 of Article X of the Trust Instrument outlines which shareholder actions must be brought in state court and which must be brought in federal court. This section states in particular that, unless the Trust consents in writing to the selection of an alternative forum, the Federal District Courts of the United States of America shall be the sole and exclusive forum for the resolution of any complaint asserting a cause of action arising under any federal securities law. This provision may increase costs for a shareholder to bring a claim or may limit a shareholder's ability to bring a claim in a judicial forum that they find more convenient or favorable. While the enforceability of the exclusive forum provisions may be challenged, this section also provides that if any provisions of Section 10 shall be held to be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining portions will still apply.

Section 10 of Article X of the Trust Instrument also states that shareholders and all other such persons bringing any such suit, action, or proceeding in the Superior Court in the State of Delaware waive the right to a trial by jury to the fullest extent permitted by law.

For more detailed information on the Fund, several additional sources of information are available to you. The Fund's SAI, incorporated by reference into this prospectus, contains detailed information on the Fund's policies and operation. Additional information about the Fund's investments is available in the annual and semi-annual reports to shareholders. In the Fund's annual reports, you will find a discussion of the market conditions and investment strategies that significantly impacted the Fund's performance during the last fiscal year. The Fund's most recent SAI, annual or semi-annual reports and certain other information are available free of charge by calling the Fund at (866) 363-9219, on the Fund's website at www.calamos.com or through your financial advisor. Shareholders may call the toll-free number above with any inquiries.

You may obtain this and other information regarding the Fund, including the SAI and Codes of Ethics adopted by the Adviser, Distributor and the Trust, directly from the SEC. Information on the SEC's website is free of charge. Visit the SEC's on-line EDGAR database at http://www.sec.gov. You may also request information regarding the Fund by sending a request (along with a duplication fee) to the SEC by sending an electronic request to [email protected].

Calamos Convertible Equity Alternative ETF

2020 Calamos Court
Naperville, IL 60563-2787
866.363.9219

www.calamos.com

SEC File #333-191151
#811-22887

CVRTSTAPRO 120224

Calamos CEF Income & Arbitrage ETF
(NYSE Arca—CCEF)

Prospectus December 2, 2024

Calamos CEF Income & Arbitrage ETF (the "Fund") is a series of the Calamos ETF Trust (the "Trust") and an exchange-traded fund ("ETF"). The Fund lists and principally trades its shares on the NYSE Arca, Inc. ("NYSE Arca" or the "Exchange").

The U.S. Securities and Exchange Commission ("SEC") has not approved or disapproved these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Table of Contents

Calamos CEF Income & Arbitrage ETF

Investment Objective

Fees and Expenses of the Fund

Annual Fund Operating Expenses (ongoing expenses that you pay each year as a percentage of the value of your investments):

Example

Portfolio Turnover

Principal Investment Strategies

Calamos CEF Income & Arbitrage ETF

Principal Risks

An investment in the Fund is subject to risks, and you could lose money on your investment in the Fund. There can be no assurance that the Fund will achieve its investment objective. You should not consider investing in the Fund if your investment objective differs from the Fund's investment objective or if you are not willing to accept the principal risks associated with an investment in the Fund. The risks associated with an investment in the Fund can increase during times of significant market volatility. Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Risks of investing in the Fund include risks associated with (1) the Fund's investment in closed-end fund shares; (2) the closed-end funds' investments; and (3) any other investments of the Fund, including investments in ETFs, BDCs, and derivative instruments. The principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a "principal risk" of investing in the Fund, regardless of the order in which it appears. The principal risks of investing in the Fund, either directly or through its investments in closed-end funds, include:

•  Anti-Takeover Provisions Risk — The closed-end funds in which the Fund invests may have organizational documents, such as a declaration of trust or by-laws, that include provisions that could limit the ability of the investors in such closed-end funds to acquire control of the closed-end fund or to change the composition of its Board. Such provisions could limit the ability of the Fund to sell such closed-end fund shares at a premium over prevailing market prices by

Calamos CEF Income & Arbitrage ETF

discouraging a third party from seeking to obtain control of the closed-end fund. These provisions may include staggered terms of office for the Trustees, advance notice requirements for shareholder proposals, and super-majority voting requirements for certain transactions with affiliates, converting the Fund to an open-end investment company or a merger, asset sale or similar transaction. Holders of preferred shares of such closed-end funds that have issued preferred shares have voting rights in addition to and separate from the voting rights of common shareholders with respect to certain of these matters. The holders of the closed-end fund debt, on the one hand, and the holders of the common shares, on the other, may have interests that conflict in these situations.

•  Arbitrage Risk — The Fund's use of an arbitrage strategy in order to take advantage of a perceived discount presents certain risks. The shares of the underlying closed-end funds in which the Fund invests may trade at a discount or premium to their NAV. Historically, shares of underlying funds have frequently traded at a discount to their NAV, which discounts have, on occasion, been substantial and lasted for sustained periods of time. This characteristic is a risk separate and distinct from the risk that an underlying fund's NAV could decrease as a result of investment activities. Whether investors, such as the Fund, will realize gains or losses upon the sale of shares will depend not on the underlying funds' NAVs, but entirely upon whether the market price of the underlying funds' shares at the time of sale is above or below an investor's purchase price for shares. Forecasting market movements is difficult, and securities may be mispriced or improperly valued by the Adviser.

•  Authorized Participant Concentration Risk — Only an Authorized Participant may engage in creation or redemption transactions directly with the Fund, and none of those Authorized Participants is obligated to engage in creation and/or redemption transactions. The Fund has a limited number of institutions that may act as Authorized Participants on an agency basis (i.e., on behalf of other market participants). To the extent that Authorized Participants exit the business or are unable to proceed with creation or redemption orders with respect to the Fund and no other Authorized Participant is able to step forward to create or redeem, Fund Shares may be more likely to trade at a premium or discount to NAV and possibly face trading halts or delisting. Authorized Participant concentration risk may be heightened for ETFs, such as the Fund, that invest in securities issued by non-U.S. issuers or other securities or instruments that have lower trading volumes.

•  Business Development Company ("BDC") Risk — The Fund may invest in BDCs, which typically operate to invest in, or lend capital to, early stage-to-mature private companies as well as small public companies. BDCs are regulated under the 1940 Act and are generally taxed as regulated investment companies under the Internal Revenue Code. BDCs realize operating income when their investments are sold off or as income is received in connection with lending, and therefore maintain complex organizational, operational, tax and compliance requirements. For tax purposes, BDCs generally intend to qualify for taxation as regulated investment companies. To so qualify, BDCs must satisfy certain asset diversification and source of income tests and must generally distribute at least 90% of their taxable earnings as dividends. Under the 1940 Act, BDCs are also required to invest at least 70% of their total assets primarily in securities of private companies or thinly traded U.S. public companies, cash, cash equivalents, U.S. government securities and high quality debt investments that mature in one year or less. Generally, little public information exists for private and thinly traded companies in which a BDC may invest, and therefore there is a risk that investors may not be able to make a fully informed decision. In addition, investments made by BDCs are typically illiquid and may be difficult to value. A BDC may only incur indebtedness in amounts such that the BDC's asset coverage, subject to certain conditions, equals at least 150% after such incurrence. These limitations on asset mix and leverage may prohibit the way that the BDC raises capital.

•  Closed-End Funds Risk — The shares of closed-end funds may trade at a discount or premium to, or at, their NAV. The securities of closed-end funds may be leveraged. As a result, the Fund, may be exposed indirectly to leverage through an investment in such securities. An investment in securities of closed-end funds that use leverage may expose the Fund to higher volatility in the market value of such securities and the possibility that the Fund's long-term returns on such securities (and, indirectly, the long-term returns of its shares) will be diminished. In addition, closed-end funds are allowed to invest in a greater amount of illiquid securities than open-end mutual funds. Investments in illiquid securities pose risks related to uncertainty in valuations, volatile market prices, and limitations on resale that may have an adverse effect on the ability of the fund to dispose of the securities promptly or at reasonable prices.

Calamos CEF Income & Arbitrage ETF

•  Convertible Securities Risk — The value of a convertible security is influenced by changes in interest rates, with investment value declining as interest rates increase and increasing as interest rates decline. The credit standing of the issuer and other factors also may have an effect on the convertible security's investment value. Convertible securities generally offer lower interest or dividend yields than non-convertible fixed-income securities of similar credit quality because of the potential for capital appreciation. In addition, the value of a convertible security is influenced by the interest rate environment, company credit risk, and by the value of the underlying common stock. As the market price of the underlying common stock declines below the conversion price, the price of the convertible security tends to be increasingly influenced by the credit quality, maturity and yield of the convertible security. Holders of convertible securities have a claim on the issuer's assets prior to the common stockholders, but may be subordinated to holders of similar but non-convertible securities of the same issuer.

•  Costs of Buying and Selling Fund Shares — Due to the costs of buying or selling Fund Shares, including brokerage commissions imposed by brokers and bid/ask spreads, frequent trading of Fund Shares may significantly reduce investment results and an investment in Fund Shares may not be advisable for investors who anticipate regularly making small investments.

•  Covered Call Writing Risk — As the writer of a covered call option on a security, the Fund foregoes, during the option's life, the opportunity to profit from increases in the market value of the security covering the call option above the sum of the premium and the exercise price of the call.

•  Currency Risk — To the extent that the Fund, or a closed-end fund in which the Fund invests, invests in securities or other instruments denominated in or indexed to foreign currencies, changes in currency exchange rates bring an added dimension of risk. Currency fluctuations could negatively impact investment gains or add to investment losses. Although the Fund or a closed-end fund in which the Fund invests may attempt to hedge against currency risk, the hedging instruments may not always perform as the Fund or a closed-end fund in which the Fund invests expects and could produce losses. Suitable hedging instruments may not be available for currencies of emerging market countries. The Adviser, or a closed-end fund's investment adviser, may determine not to hedge currency risks, even if suitable instruments appear to be available.

•  Debt Securities Risk — Debt securities are subject to various risks, including interest rate risk, credit risk and default risk.

•  Interest Rate Risk — The value of debt securities generally decreases in periods when interest rates are rising. In addition, interest rate changes typically have a greater effect on prices of longer-term debt securities than shorter term debt securities. Recent fixed-income market events, including increases in volatility and interest rates, may expose the Fund to heightened interest rate risk and volatility.

•  Credit Risk — A debt security could deteriorate in quality to such an extent that its rating is downgraded or its market value declines relative to comparable securities. Changes in actual or perceived creditworthiness may occur quickly. If the Fund holds securities that have been downgraded, or that default on payment, the Fund's performance could be negatively affected.

•  Default Risk — A company that issues a debt security may be unable to fulfill its obligation to repay principal and interest. The lower a bond is rated, the greater its default risk. To the extent the Fund holds securities that have been downgraded, or that default on payment, its performance could be negatively affected.

•  Derivatives Risk — Derivatives are instruments, such as futures and forward foreign currency contracts, whose value is derived from that of other assets, rates or indices. The use of derivatives for non-hedging purposes may be considered more speculative than other types of investments. Derivatives can be used for hedging (attempting to reduce risk by offsetting one investment position with another) or non-hedging purposes. Hedging with derivatives may increase expenses, and there is no guarantee that a hedging strategy will work. While hedging can reduce or eliminate losses, it can also reduce or eliminate gains. In addition, derivative instruments are subject to counterparty risk, meaning that the party with whom the Fund, or a closed-end fund in which the fund invests, enters into the derivatives transaction may experience a significant credit event and/or may be unwilling or unable to make timely settlement payments or otherwise honor its obligations. Changes in the value of a derivative may not correlate perfectly with the underlying asset, rate or index, and the Fund, or a closed-end fund in which the fund invests, could lose more than the principal amount invested.

Calamos CEF Income & Arbitrage ETF

•  Emerging Markets Risk — Emerging market countries may have relatively unstable governments and economies based on only a few industries, which may cause greater instability. The value of emerging market securities will likely be particularly sensitive to changes in the economies of such countries. These countries are also more likely to experience higher levels of inflation, deflation or currency devaluations, which could hurt their economies and securities markets. Securities issued in these countries may be more volatile and less liquid than securities issued in foreign countries with more developed economies or markets. Loss may also result from the imposition of exchange controls, confiscations and other government restrictions, or from problems in share registration, settlement, custody, or other operational risks.

•  Equity Securities Risk — The securities markets are volatile, and the market prices of each closed-end fund's securities may decline generally. The price of equity securities fluctuates based on changes in a company's financial condition and overall market and economic conditions. If the market prices of the securities owned by a closed-end fund fall, the value of your investment in the Fund will decline.

•  ETF Risk — The Fund's investment in shares of ETFs subjects it to the risks of owning the securities underlying the ETF, as well as the same structural risks faced by an investor purchasing shares of the Fund, including authorized participant concentration risk, market maker risk, premium-discount risk and trading issues risk. As a shareholder in another ETF, the Fund bears its proportionate share of the ETF's expenses, subjecting Fund shareholders to duplicative expenses.

•  Foreign Securities Risk — Risks associated with investing in foreign securities include fluctuations in the exchange rates of foreign currencies that may affect the U.S. dollar value of a security, the possibility of substantial price volatility as a result of political and economic instability in the foreign country, less public information about issuers of securities, different securities regulation, different accounting, auditing and financial reporting standards and less liquidity than in U.S. markets.

•  Fund of Funds Risk — Because the Fund is a "fund of funds," its investment performance largely depends on the investment performance of the funds in which it invests. An investment in the Fund is subject to the risks associated with such funds. Therefore, there is a risk that the Fund may suffer losses due to the investment practices or operations of the funds in which it invests. To the extent that the Fund invests in one or more funds that concentrate in a particular type of security or specific industry, the Fund would be exposed to such specific securities' risks and be vulnerable to factors affecting that industry and may cause the Fund to be more volatile than other funds. The funds held by the Fund are not subject to the Fund's investment policies and restrictions. The Fund generally receives information regarding the portfolio holdings of such funds only when that information is made available to the public. The Fund cannot dictate how such funds invest their assets. The funds may invest their assets in securities and other instruments, and may use investment techniques and strategies, that are not described in this disclosure.

The Fund will pay indirectly a proportional share of the fees and expenses of the funds in which it invests (referred to herein as "acquired fund fees and expenses"), including their investment advisory and administration fees, in addition to its own fees and expenses. In addition, at times, certain segments of the market represented by the funds in which the Fund invests may be out of favor and underperform other segments.

•  Futures and Forward Contracts Risk — Futures contracts provide for the future sale by one party and purchase by another of a specific asset at a specific time and price (with or without delivery required). Futures contracts are standardized contracts traded on a recognized exchange. An option on a futures contract gives the purchaser the right, in exchange for a premium, to assume a position in a futures contract at a specified exercise price during the term of the option. Futures and forward contracts are subject to counterparty risk, meaning that the party with whom the Fund enters into the derivatives transaction (the clearinghouse or the broker holding the Fund's position for a futures contract or the counterparty for a forward contract) may experience a significant credit event and/or may be unwilling or unable to make timely settlement payments or otherwise honor its obligations.

•  High Yield Risk — High yield securities and unrated securities of similar credit quality (commonly known as "junk bonds") are subject to greater levels of credit and liquidity risks. High yield securities are considered primarily speculative with respect to the issuer's continuing ability to make principal and interest payments.

•  Large-Capitalization Investing Risk — Large-capitalization stocks as a group could fall out of favor with the market, which may cause a closed-end fund in which the Fund invests to underperform funds that focus on other types of stocks.

Calamos CEF Income & Arbitrage ETF

In addition, larger, more established companies may be unable to respond quickly to new competitive challenges such as changes in technology and consumer preferences. Many larger companies also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

•  Liquidity Risk — Liquidity risk exists when particular investments are difficult to purchase or sell. The Fund's investments in illiquid securities may reduce the returns of the Fund because it may be unable to sell the illiquid securities at an advantageous time or price.

•  Market Maker Risk — If the Fund has lower average daily trading volumes, it may rely on a small number of third-party market makers to provide a market for the purchase and sale of Fund Shares. Any trading halt or other problem relating to the trading activity of these market makers could result in a dramatic change in the spread between the Fund's net asset value and the price at which the Fund Shares are trading on the Exchange, which could result in a decrease in value of the Fund Shares. In addition, decisions by market makers or authorized participants to reduce their role or step away from these activities in times of market stress could inhibit the effectiveness of the arbitrage process in maintaining the relationship between the underlying values of the Fund's portfolio securities and the Fund's market price. This reduced effectiveness could result in Fund Shares trading at a discount to net asset value and also in greater than normal intra-day bid-ask spreads for Fund Shares.

•  Market Risk — The risk that the securities markets will increase or decrease in value is considered market risk and applies to any security. If there is a general decline in the stock or fixed-income market, it is possible your investment may lose value regardless of the individual results of the companies in which the Fund invests.

•  MLP Risk — Investments in securities of MLPs involve risks that differ from investments in common stock, including risks related to limited control and limited rights to vote on matters affecting the MLP, risks related to the potential conflicts of interest between the MLP and the MLP's general partners, cash flow risks, dilution risks and risks related to the general partners right to require unit holders to sell their common units at an undesirable time or price.

•  MLP Tax Risk — MLPs generally do not pay federal income tax at the partnership level. Rather, each partner is allocated a share of the partnerships' income, gains, losses, deductions and credits. A change in current tax law, or a change in the underlying business of an MLP, could result in an MLP being treated as a corporation, instead of a partnership, for federal income tax purposes, which would result in such MLP being required to pay income tax on its taxable income. This would have the effect of reducing the amount of cash available for distribution by the MLP, potentially reducing the value of the Fund's investment and consequently your investment in the Fund.

•  MLP Liquidity Risk — Although common units of MLPs trade on the NYSE, the NASDAQ and Amex, certain MLP securities trade less frequently than those of larger companies due to their smaller capitalization. As a result, the price of such MLPs may display abrupt and erratic movements at times. Additionally it may be more difficult for the Fund to buy and sell significant amounts of such securities without unfavorable impact on prevailing market process. As a result, these securities may be difficult to dispose of at a fair price when the Adviser desires to do so. This may adversely affect the Fund's ability to take advantage of other market opportunities or make dividend distributions.

•  Equity Securities of MLPs Risk — MLP common units, like other equity securities, can be affected by macro-economic and other factors affecting the stock market in general, expectations of interest rates, investor sentiment towards an issuer or certain market sector, changes in a particular issuer's financial condition, or unfavorable or unanticipated poor performance of a particular issuer (in the case of MLPs, generally measured in terms of distributable cash flow). Prices of common units of individual MLPs, like the prices other equity securities, also can be affected by fundamentals unique to the partnership or company, including earnings power and coverage ratios.

•  Municipal Securities Risk — The Fund may invest in closed-end funds and/or ETFs that hold municipal securities. Issuers, including governmental issuers, may be unable to pay their obligations as they come due. The values of municipal securities that depend on a specific revenue source to fund their payment obligations may fluctuate as a result of actual or anticipated changes in the cash flows generated by the revenue source or changes in the priority of the municipal obligation to receive the cash flows generated by the revenue source. The values of municipal securities held by an underlying fund may be adversely affected by local political and economic conditions and developments. Adverse

Calamos CEF Income & Arbitrage ETF

conditions in an industry significant to a local economy could have a correspondingly adverse effect on the financial condition of local issuers. In addition, income from municipal securities held by an underlying fund could be declared taxable because of, among other things, unfavorable changes in tax laws, adverse interpretations by the Internal Revenue Service or state tax authorities, or noncompliant conduct of an issuer or other obligated party. Loss of tax-exempt status may cause interest received and distributed to shareholders by an underlying fund to be taxable and may result in a significant decline in the values of such municipal securities. Due to the COVID-19 pandemic, the risks of the municipal securities market have been magnified. The costs associated with combating the pandemic and the negative impact on tax revenues has adversely affected the financial condition of many states and political subdivisions. These risks may also adversely affect several sectors of the municipal bond market, such as airports, toll roads, hospitals and colleges, among many others. The full impact of the COVID-19 pandemic on state and political subdivisions' ability to make payments on debt obligations is impossible to predict, but could negatively impact the value of bonds, the ability of state and political subdivisions to make payments when due and the performance of the Fund.

•  National Closed Market Trading Risk — To the extent that the underlying securities and/or other assets held by the Fund trade on non-U.S. exchanges or in non-U.S. markets that may be closed when the securities exchange on which Fund Shares trade is open, there are likely to be deviations between the current price of such an underlying security and the last quoted price for the underlying security (i.e., the Fund's quote from the closed non-U.S. market). The impact of a closed foreign market on the Fund is likely to be greater where a large portion of the Fund's underlying securities and/or other assets trade on that closed non-U.S. market or when the non-U.S. market is closed for unscheduled reasons. These deviations could result in premiums or discounts to the Fund's NAV that may be greater than those experienced by other ETFs.

•  New Fund Risk — The Fund is a recently organized investment company with a limited operating history. As a result, prospective investors have a limited track record or history on which to base their investment decision.

•  Non-Diversification Risk — The Fund is classified as "non-diversified" under the 1940 Act. As a result, the Fund is only limited as to the percentage of its assets which may be invested in the securities of any one issuer by the diversification requirements imposed by the Internal Revenue Code of 1986, as amended.

•  Options Risk — The Fund's ability to close out its position as a purchaser or seller of an over-the-counter or exchange-listed put or call option is dependent, in part, upon the liquidity of the option market. There are significant differences between the securities and options markets that could result in an imperfect correlation among these markets, causing a given transaction not to achieve its objectives. The Fund's ability to utilize options successfully will depend on the ability of the Fund's investment adviser to predict pertinent market movements, which cannot be assured.

•  Other Investment Companies (including closed-end funds, ETFs and BDCs) Risk — The Fund invests in the securities of other investment companies (including closed-end funds, ETFs, and BDCs) consistent with the Fund's investment objective and the policies are permissible under the 1940 Act. Investments in the securities of other investment companies may involve duplication of advisory fees and certain other expenses. Additionally, if the investment company fails to achieve its investment objective, the value of the Fund's investment will decline, adversely affecting the Fund's performance. In addition, closed-end funds, ETF, and BDC shares potentially may trade at a discount or a premium and are subject to brokerage and other trading costs, which could result in greater expenses to the Fund. Whether the Fund will realize a gain or loss upon the sale of the such shares of closed-end funds, ETFs and BDCs depends upon whether the market value of the shares at the time of sale is above or below the price the Fund paid, taking into account transaction costs for the shares, and is not directly dependent upon the NAV of the shares of such funds. Because the market value of the shares will be determined by factors such as the relative demand for and supply of the shares in the market, general market conditions and other factors, it cannot be predicted whether such shares will trade at, below or above NAV, or below or above the public offering price for the shares. Common Shares, as well as shares issued by the closed-end funds, do not assure dividend payments. Dividends are paid only when declared by the boards of directors of the closed-end funds, and the level of dividends may vary over time. If a closed-end fund reduces or eliminates the level of its regular dividends, this may reduce the level of dividends paid by the Fund, and may cause the market prices of the closed-end fund's shares to fall.

Calamos CEF Income & Arbitrage ETF

In accordance with Section 12(d)(1)(F) of the 1940 Act, on which the Fund intends to rely to invest in other investment companies, the Fund will be restricted by provisions of the 1940 Act that limit the amount the Fund can invest in any one investment company to 3% of the investment company's total outstanding stock. As a result, the Fund may hold a smaller position in an investment company than if it were not subject to this restriction. However, if the Adviser determines that it is in the Fund's best interest to exceed the 3% limit, it may rely on Rule 12d1-4 under the 1940 Act. Rule 12d1-4 would permit the Fund to invest in excess of the 3% limit subject to certain conditions, including that the Fund must enter into a "Fund of Funds Investment Agreement" with the acquired investment company setting forth the material terms of the arrangement. In addition, to comply with provisions of the 1940 Act, on any matter upon which investment company stockholders are solicited to vote, the Adviser will vote investment company shares in the same general proportion as shares held by other stockholders of the investment company (a practice known as "echo voting"). This could limit the Fund's ability to support or oppose investment company shareholder voting matters.

•  Portfolio Selection Risk — The value of your investment may decrease if Calamos Advisors' judgment about the attractiveness, value or market trends affecting a particular security, issuer, industry or sector or about market movements is incorrect.

•  Portfolio Turnover Risk — The portfolio managers may actively and frequently trade securities or other instruments in the Fund's portfolio to carry out its investment strategies. A high portfolio turnover rate increases transaction costs, which may increase the Fund's expenses. Frequent and active trading may also cause adverse tax consequences for investors in the Fund due to an increase in short-term capital gains.

•  Premium-Discount Risk — Fund Shares may trade above or below their net asset value ("NAV"). The market prices of Fund Shares will generally fluctuate in accordance with changes in NAV as well as the relative supply of, and demand for, Fund Shares on the Exchange. The trading price of Fund Shares may deviate significantly from NAV during periods of market volatility.

•  Secondary Market Trading Risk — Investors buying or selling Fund Shares in the secondary market will pay brokerage commissions or other charges imposed by brokers as determined by that broker. Brokerage commissions are often a fixed amount and may be a significant proportional cost for investors seeking to buy or sell relatively small amounts of Fund Shares. Although the Fund Shares are listed on the Exchange, there can be no assurance that an active or liquid trading market for them will develop or be maintained. In addition, trading in Fund Shares on the Exchange may be halted.

•  Sector Risk — To the extent the Fund invests a significant portion of its assets in a particular sector, a greater portion of the Fund's performance may be affected by the general business and economic conditions affecting that sector. Each sector may share economic risk with the broader market, however there may be economic risks specific to each sector. As a result, returns from those sectors may trail returns from the overall stock market, and it is possible that the Fund may underperform the broader market or experience greater volatility.

•  Short Sale Risk — The Fund may incur a loss (without limit) as a result of a short sale if the market value of the borrowed security (i.e., the Fund's short position) increases between the date of the short sale and the date the Fund replaces the security. The Fund may be unable to repurchase the borrowed security at a particular time or at an acceptable price.

•  Tax Risk — The Fund intends to elect and to qualify each year to be treated as a regulated investment company under Subchapter M of the Internal Revenue Code of 1986, as amended (the "Code"). The federal income tax treatment of securities in which the Fund may invest may not be clear or may be subject to recharacterization by the Internal Revenue Service. It could be more difficult to comply with the tax requirements applicable to regulated investment companies if the tax characterization of investments or the tax treatment of the income from such investments were successfully challenged by the Internal Revenue Service. Any such failure to comply with the rules applicable to regulated investment companies could cause the Fund to fail to qualify as such. If the Fund does not qualify as a regulated investment company for any taxable year, and certain relief provisions are not available, the Fund's taxable income will be subject to tax at the Fund level and to a further tax at the shareholder level when such income is distributed.

•  Trading Issues Risk — Trading in Fund Shares on the Exchange may be halted due to market conditions or for reasons that, in the view of the Exchange, make trading in shares inadvisable. In addition, trading in Fund Shares on the Exchange

Calamos CEF Income & Arbitrage ETF

is subject to trading halts caused by extraordinary market volatility pursuant to the Exchange's "circuit breaker" rules. There can be no assurance that the requirements of the Exchange necessary to maintain the listing of the Fund will continue to be met or will remain unchanged. The Fund may have difficulty maintaining its listing on the Exchange in the event the Fund's assets are small, the Fund does not have enough shareholders, or if the Fund is unable to proceed with creation and/or redemption orders.

Fund Performance

Investment Adviser

Calamos Advisors LLC ("Calamos Advisors" or the "Adviser")

Portfolio Managers

Other Important Information Regarding Fund Shares

Portfolio Holdings. The Fund's portfolio holdings are disclosed on its website daily after the close of trading on the Exchange and prior to the opening of trading on the Exchange the following day. A description of the Fund's policies and procedures with respect to the disclosure of the Fund's portfolio holdings is available in the Fund's Statement of Additional Information ("SAI").

Premium/Discount Information. Information about the premiums and discounts at which the Fund's Shares have traded will be available at www.calamos.com.

Purchase and Sale of Fund Shares

The Fund will issue (or redeem) Fund Shares to certain institutional investors (typically market makers or other broker-dealers) only in large blocks of Fund Shares known as "Creation Units." Creation Unit transactions are conducted in exchange for the deposit or delivery of a designated portfolio of in-kind securities and/or cash.

Individual Fund Shares may only be purchased and sold on the Exchange, other national securities exchanges, electronic crossing networks and other alternative trading systems through your broker-dealer at market prices. Because Fund Shares trade at market prices rather than at net asset value ("NAV"), Fund Shares may trade at a price greater than NAV (premium) or less than NAV (discount). When buying or selling Fund Shares in the secondary market, you may incur costs attributable to the difference between the highest price a buyer is willing to pay to purchase Fund Shares (bid) and the lowest price a seller is willing to accept for Fund Shares (ask) (the "bid-ask spread"). Recent information regarding the Fund's NAV, market price, premiums and discounts, and bid-ask spreads is available at https://www.calamos.com/.

Tax Information

Net investment income and capital gains distributions you receive from the Fund generally are subject to federal income taxes and may also be subject to state and local taxes. The Fund expects to declare and distribute its net investment income, if any, to shareholders as dividends monthly. The Fund may distribute such investment income more frequently, if necessary, in order to reduce or eliminate federal excise or income taxes on the Fund. The Fund expects to declare and distribute capital gains, if any, on an annual basis.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase shares of the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies may pay the intermediary for the sale of Fund Shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary's website for more information.

Additional Information About Investment Strategies and Related Risks

The Fund's investment objective, the 80% investment strategy and each of the policies described herein are non-fundamental policies that may be changed by the Board of Trustees of the Trust (the "Board") without shareholder approval. The Fund may liquidate and terminate at any time without shareholder approval.

What are the investment objective and principal strategies for the Fund?

The Fund's investment objective is high current income and long-term capital appreciation.

The Fund is an actively managed ETF that seeks high current income and long-term capital appreciation by investing in unaffiliated closed-end funds that the Fund's investment adviser, Calamos Advisors, believes offer both attractive income opportunities as well as arbitrage opportunities resulting from such closed-end funds trading at attractive discounts (market prices that are less than the closed-end funds' NAV). The Fund's strategy seeks to identify closed-end funds trading at attractive discounts and sell such funds when the arbitrage opportunity has either been achieved by capturing the benefit of discount narrowing or when the Adviser determines the discount level no longer represents an unusual divergence from the fund's underlying asset value. Under normal circumstances, the Fund seeks to achieve its investment objectives by investing at least 80% of its net assets (plus borrowings for investment purposes, if any) in U.S. and non-U.S. closed-end funds.

In selecting the closed-end funds for the Fund's portfolio, the Adviser utilizes a combination of quantitative and fundamental tools to identify closed-end funds that are trading at a discount and represent an opportunity for the Fund to achieve its investment objective. In addition, the Adviser considers the Fund's asset allocation, event research (both fund-specific and market-wide), and trading opportunities (i.e., the liquidity profile of a closed-end fund). The Adviser intends to rebalance the portfolio regularly to ensure that the desired asset allocations are maintained. The Adviser will also make active adjustments to the portfolio relative to certain portfolio-level characteristics, that may include, but are not limited to, distribution yield, size of an issue, liquidity and trade execution.

The Fund also may invest in ETFs and BDCs. Through its investments in closed-end funds, ETFs, and BDCs, the Fund may have exposure to different asset classes, including but not limited to equity securities (U.S. and non-U.S., including emerging markets), fixed income securities (investment grade, high yield, and municipal), convertible securities, derivatives and MLPs. Fixed income securities may include bonds and debentures that may be rated investment grade or below investment grade or may not be rated, may be issued by corporations, governments or public international bodies and may be denominated in a variety of currencies and issued with either fixed or floating rates. Bonds rated below investment grade are commonly known as "junk bonds."

The Fund may invest in rights or warrants of equity securities and closed-end funds. The Fund also may use derivative instruments such as options, index futures, and forward contracts. The Fund may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis.

In order to capture the relative arbitrage value embedded in the discount, the Fund may from time to time take short positions that approximate the value of the underlying closed-end fund assets. The Fund also may take other short positions, including in U.S. treasury futures. The Fund may maintain short positions through the use of derivative instruments, such as options and futures.

The Fund may seek to generate income from option premiums by writing (selling) options. This would include the use of both call and put options. The Fund may write call options (i) on a portion of the equity securities (including securities that are convertible into equity securities) in the Fund's portfolio and (ii) on broad-based securities indexes (such as the S&P 500 or MSCI EAFE) or ETFs. In addition, to seek to offset some of the risk of a potential decline in value of certain long positions, the Fund may also purchase put options on individual securities, broad-based securities indexes (such as the S&P 500), or ETFs.

The Fund is classified as "non-diversified" under the Investment Company Act of 1940, as amended (the "1940 Act").

Additional Information About Investment Strategies and Related Risks

Non-Principal Investments

Temporary Investments

In response to market, economic, political, or other conditions, the Fund may temporarily invest for defensive purposes. If the Fund does so, different factors could affect the Fund's performance, and the Fund may not achieve its investment objective.

Illiquid Investments

The Fund may invest up to 15% of its net assets in securities and other instruments that are, at the time of investment, illiquid (determined using the Securities and Exchange Commission's standard applicable to investment companies, i.e., any investment that the Fund reasonably expects cannot be sold or disposed of in current market conditions in seven calendar days or less without the sale or disposition significantly changing the market value of the investment). For this purpose, illiquid investments may include, but are not limited to, certain restricted securities (securities the disposition of which is restricted under the federal securities laws), certain securities that may only be resold pursuant to Rule 144A under the Securities Act, and certain repurchase agreements, among others.

Changes in 80% policy

The Fund has adopted a non-fundamental operating policy that requires it, under normal circumstances, to invest at least 80% of its net assets (plus borrowings for investment purposes, if any) in U.S. and non-U.S. closed-end funds. Although this requirement may be changed by the Board of Trustees without shareholder approval, the Fund will notify shareholders in writing at least 60 days prior to any change in its 80% policy.

Risks of Investing in the Fund

This prospectus describes the risks you may face as an investor in the Fund. It is important to keep in mind that generally, investments with a higher potential reward also have a higher risk of losing money. The reverse is also commonly true: the lower the risk, the lower the potential reward. However, as you consider an investment in the Fund, you should also take into account your tolerance for the daily fluctuations of the financial markets and whether you can afford to leave your money in this investment for a long period of time to ride out down periods.

As with any security, there are market and investment risks associated with your investment in the Fund. The value of your investment will fluctuate over time, and it is possible to lose money. Risks of investing in the Fund include risks associated with (1) in the Fund's investment in closed-end fund shares; (2) the risks of the closed-end funds' investments; and (3) any other investments of the Fund, including investments in ETFs, BDCs, and derivative instruments. The principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a "principal risk" of investing in the Fund, regardless of the order in which it appears. The principal risks of investing in the Fund, either directly or through its investments in closed-end funds, include:

Principal Risks

Anti-Takeover Provisions Risk. The closed-end funds in which the Fund invests may have organizational documents, such as a declaration of trust or by-laws, that include provisions that could limit the ability of the investors in such closed-end funds to acquire control of the closed-end fund or to change the composition of its Board. Such provisions could limit the ability of the Fund to sell such closed-end fund shares at a premium over prevailing market prices by discouraging a third party from seeking to obtain control of the closed-end fund. These provisions may include staggered terms of office for the Trustees, advance notice requirements for shareholder proposals, and super-majority voting requirements for certain transactions with affiliates, converting the Fund to an open-end investment company or a merger, asset sale or similar transaction. Holders of preferred shares of such closed-end funds that have issued preferred shares have voting rights in addition to and separate from the voting rights of common shareholders with respect to certain of these matters. The holders of the closed-end fund debt, on the one hand, and the holders of the common shares, on the other, may have interests that conflict in these situations.

Arbitrage Risk. The Fund's use of an arbitrage strategy in order to take advantage of a perceived discount presents certain risks. The shares of the underlying closed-end funds in which the Fund invests may trade at a discount or premium to their NAV. Historically, shares of underlying funds have frequently traded at a discount to their NAV, which discounts have, on occasion, been substantial and lasted for sustained periods of time. This characteristic is a risk separate and distinct from the

Additional Information About Investment Strategies and Related Risks

risk that an underlying fund's NAV could decrease as a result of investment activities. Whether investors, such as the Fund, will realize gains or losses upon the sale of shares will depend not on the underlying funds' NAVs, but entirely upon whether the market price of the underlying funds' shares at the time of sale is above or below an investor's purchase price for shares. Forecasting market movements is difficult, and securities may be mispriced or improperly valued by the Adviser.

Authorized Participant Concentration Risk. Only an Authorized Participant may engage in creation or redemption transactions directly with the Fund, and none of those Authorized Participants is obligated to engage in creation and/or redemption transactions. The Fund has a limited number of institutions that may act as Authorized Participants on an agency basis (i.e., on behalf of other market participants). To the extent that Authorized Participants exit the business or are unable to proceed with creation or redemption orders with respect to the Fund and no other Authorized Participant is able to step forward to create or redeem, Fund Shares may be more likely to trade at a premium or discount to NAV and possibly face trading halts or delisting. Authorized Participant concentration risk may be heightened for ETFs, such as the Fund, that invest in securities issued by non-U.S. issuers or other securities or instruments that have lower trading volumes.

Business Development Company ("BDC") Risk. The Fund may invest in BDCs, which typically operate to invest in, or lend capital to, early stage-to-mature private companies as well as small public companies. BDCs are regulated under the 1940 Act and are generally taxed as regulated investment companies under the Internal Revenue Code. BDCs realize operating income when their investments are sold off or as income is received in connection with lending, and therefore maintain complex organizational, operational, tax and compliance requirements. For tax purposes, BDCs generally intend to qualify for taxation as regulated investment companies. To so qualify, BDCs must satisfy certain asset diversification and source of income tests and must generally distribute at least 90% of their taxable earnings as dividends. Under the 1940 Act, BDCs are also required to invest at least 70% of their total assets primarily in securities of private companies or thinly traded U.S. public companies, cash, cash equivalents, U.S. government securities and high quality debt investments that mature in one year or less. Generally, little public information exists for private and thinly traded companies in which a BDC may invest, and therefore there is a risk that investors may not be able to make a fully informed decision. In addition, investments made by BDCs are typically illiquid and may be difficult to value. A BDC may only incur indebtedness in amounts such that the BDC's asset coverage, subject to certain conditions, equals at least 150% after such incurrence. These limitations on asset mix and leverage may prohibit the way that the BDC raises capital.

Closed-End Funds Risk. The shares of closed-end funds may trade at a discount or premium to, or at, their NAV. The securities of closed-end funds may be leveraged. As a result, the Fund, may be exposed indirectly to leverage through an investment in such securities. An investment in securities of closed-end funds that use leverage may expose the Fund to higher volatility in the market value of such securities and the possibility that the Fund's long-term returns on such securities (and, indirectly, the long-term returns of its shares) will be diminished. In addition, closed-end funds are allowed to invest in a greater amount of illiquid securities than open-end mutual funds. Investments in illiquid securities pose risks related to uncertainty in valuations, volatile market prices, and limitations on resale that may have an adverse effect on the ability of the fund to dispose of the securities promptly or at reasonable prices.

Convertible Securities Risk. The value of a convertible security is influenced by both the yield of non-convertible securities of comparable issuers and by the value of the underlying common stock. The value of a convertible security viewed without regard to its conversion feature (i.e., strictly on the basis of its yield) is sometimes referred to as its "investment value." A convertible security's investment value tends to decline as prevailing interest rate levels increase. Conversely, a convertible security's investment value increases as prevailing interest rate levels decline. However, a convertible security's market value will also be influenced by its "conversion value," which is the market value of the underlying common stock that would be obtained if the convertible security were converted. A convertible security's conversion value tends to increase as the price of the underlying common stock increases, and decrease as the price of the underlying common stock decreases.

As the market price of the underlying common stock declines such that the conversion value is substantially below the investment value of the convertible security, the price of the convertible security tends to be influenced more by the yield of the convertible security. Thus, it may not decline in price to the same extent as the underlying common stock.

Additional Information About Investment Strategies and Related Risks

If the market price of the underlying common stock increases to a point where the conversion value approximates or exceeds the investment value, the price of the convertible security tends to be influenced more by the market price of the underlying common stock. In the event of a liquidation of the issuing company, holders of convertible securities would be paid before the company's common stockholders. Consequently, the issuer's convertible securities entail less risk than its common stock.

Costs of Buying and Selling Fund Shares. Due to the costs of buying or selling Fund Shares, including brokerage commissions imposed by brokers and bid/ask spreads, frequent trading of Fund Shares may significantly reduce investment results and an investment in Fund Shares may not be advisable for investors who anticipate regularly making small investments.

Covered Call Writing Risk. As the writer of a covered call option on a security, the Fund foregoes, during the option's life, the opportunity to profit from increases in the market value of the security covering the call option above the sum of the premium and the exercise price of the call.

Currency Risk. To the extent that the Fund, or a closed-end fund in which the Fund invests, invests in securities or other instruments denominated in or indexed to foreign currencies, changes in currency exchange rates bring an added dimension of risk. Currency fluctuations could negatively impact investment gains or add to investment losses. Although the Fund or a closed-end fund in which the Fund invests may attempt to hedge against currency risk, the hedging instruments may not always perform as the Fund or a closed-end fund in which the Fund invests expects and could produce losses. Suitable hedging instruments may not be available for currencies of emerging market countries. The Adviser, or a closed-end fund's investment adviser, may determine not to hedge currency risks, even if suitable instruments appear to be available.

Debt Securities Risk. Debt securities are subject to various risks, including interest rate risk, credit risk and default risk.

Interest Rate Risk. Interest rate risk is the risk that the Fund's investments in debt securities will decrease in value as a result of an increase in interest rates. Generally, there is an inverse relationship between the value of a debt security and interest rates. Therefore, the value of debt securities generally decrease in periods when interest rates are rising. In addition, interest rate changes typically have a greater effect on prices of longer-term debt securities than shorter-term debt securities. Recent fixed- income market events, including changes in interest rates by the Federal Reserve Board, may subject the Fund to heightened interest rate risk as a result of a rise in interest rates. In addition, the Fund is subject to the risk that interest rates may exhibit increased volatility, which could cause the Fund's net asset value to fluctuate more. A decrease in fixed-income market maker capacity may act to decrease liquidity in the fixed-income markets and act to further increase volatility, affecting the Fund's return. Many financial instruments use or may use a floating rate which historically had been based on the London Interbank Offered Rate ("LIBOR"), which was the offered rate for short-term Eurodollar deposits between major international banks. In connection with the global transition away from LIBOR led by regulators and market participants, LIBOR was last published on a representative basis at the end of June 2023. Actions by regulators have resulted in the establishment of alternative reference rates to LIBOR, such as the Secured Overnight Financing Rate (SOFR), and the transition to new reference rates continues. The transition away from LIBOR and the use of replacement rates has gone relatively smoothly, but the full impact of the transition away from LIBOR on the Fund or the financial instruments in which the Fund invests cannot yet be fully determined.

Credit Risk. Credit risk is the risk that a debt security could deteriorate in quality to such an extent that its rating is downgraded or its market value declines relative to comparable securities. Changes in actual or perceived creditworthiness may occur quickly. If the Fund holds securities that have been downgraded, or that default on payment, such Fund's performance could be negatively affected.

Default Risk. Default risk refers to the risk that a company that issues a debt security will be unable to fulfill its obligation to repay principal and interest. The lower a bond is rated, the greater its default risk. To the extent the Fund holds securities that have been downgraded, or that default on payment, its performance could be negatively affected.

Derivatives Risk. Derivatives are instruments, such as futures and forward foreign currency contracts, whose value is derived from that of other assets, rates or indices. Derivatives may be more volatile than other investments and may magnify the Fund's gains or losses. Successful use of derivatives depends upon the level to which prices of the underlying assets correlate with price movements in the derivatives the Fund, or a closed-end fund in which the Fund invests, buys or sells. The Fund, or a

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closed-end fund in which the Fund invests, could be negatively affected if the change in market value of its securities fails to correlate with the value of derivatives it purchased or sold. The potential lack of a liquid market for a derivative may prevent the Fund, or a closed-end fund in which the Fund invests, from closing its derivatives positions to limit losses or realize profits. Derivatives may be purchased for a fraction of their value and small price movements may result in an immediate and substantial loss to the Fund or a closed-end fund in which the Fund invests.

The use of derivatives for non-hedging purposes may be considered more speculative than other types of investments. Derivatives can be used for hedging (attempting to reduce risk by offsetting one investment position with another) or non-hedging purposes. Hedging with derivatives may increase expenses, and there is no guarantee that a hedging strategy will work. While hedging can reduce or eliminate losses, it can also reduce or eliminate gains. In addition, derivative instruments are subject to counterparty risk, meaning that the party with whom the Fund, or a closed-end fund in which the Fund invests, enters into the derivatives transaction (e.g., the clearinghouse or the broker holding the Fund's, or a closed-end fund's, position for a futures contract or the counterparty for a forward contract) may experience a significant credit event and/or may be unwilling or unable to make timely settlement payments or otherwise honor its obligations. Changes in the value of a derivative may not correlate perfectly with the underlying asset, rate or index, and the Fund, or a closed-end fund in which the Fund invests, could lose more than the principal amount invested.

Emerging Markets Risk. Investment in foreign securities may include investment in securities of foreign issuers located in less developed countries, which are sometimes referred to as emerging markets. Emerging market countries may have relatively unstable governments and economies based on only a few industries, which may cause greater instability. The value of emerging market securities will likely be particularly sensitive to changes in the economies of such countries (such as reversals of economic liberalization, political unrest or changes in trading status). These countries are also more likely to experience higher levels of inflation, deflation or currency devaluations, which could hurt their economies and securities markets. Certain emerging markets are sometimes referred to as "frontier markets." Frontier markets, the least advanced capital markets in the developing world, are among the riskiest markets in the world in which to invest. Frontier markets have the fewest number of investors and investment holdings and may not even have stock markets on which to trade. Investments in this sector are typically illiquid, nontransparent and subject to very low regulation levels as well as high transaction fees, and may also have substantial political and currency risk. Emerging and frontier markets both offer the prospect of higher returns with higher risk. However, emerging markets are more stable and developed than frontier markets. The economies of emerging market countries have achieved a rudimentary level of development, while frontier markets represent the least economically developed nations in the global marketplace. Emerging and frontier markets also carry several types of investment risk, including market, political and currency risk, as well as the risk of nationalization.

Equity Securities Risk. Equity investments are subject to greater fluctuations in market value than other asset classes as a result of such factors as a company's business performance, investor perceptions, stock market trends and general economic conditions.

ETF Risk. The Fund may invest in ETFs. Many ETFs use a "passive" investment strategy and seek to replicate the performance of a market index. Such ETFs do not take defensive positions in volatile or declining markets their shares may trade below net asset value. While some ETFs seek to achieve the same return as a particular market index, the performance of the ETF may diverge from the performance of the index. Some ETFs are actively managed ETFs and do not track a particular index which indirectly subjects an investor to active management risk. An active secondary market in ETF shares may not develop or be maintained and may be halted or interrupted due to actions by its listing exchange, unusual market conditions or other reasons. There can be no assurance that an ETF's shares will continue to be listed on an active exchange. In addition, shareholders bear both their proportionate share of the Fund's expenses and, indirectly, the ETF's expenses, incurred through the Fund's ownership of the ETF. Because the expenses and costs of an ETF are shared by its investors, redemptions by other investors in the ETF could result in decreased economies of scale and increased operating expenses for such ETF. These transactions might also result in higher brokerage, tax or other costs for the ETF. This risk may be particularly important when one investor owns a substantial portion of the ETF. There is a risk that ETFs in which the Fund invests may terminate due to extraordinary events. For example, any of the service providers to ETFs, such as the trustee or sponsor, may close or otherwise fail to perform their obligations to the ETF, and the ETF may not be able to find a substitute service provider. Also, certain ETFs

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may be dependent upon licenses to use various indexes as a basis for determining their compositions and/or otherwise to use certain trade names. If these licenses are terminated, the ETFs may also terminate. In addition, an ETF may terminate if its net assets fall below a certain amount.

Foreign Securities Risk. There are special risks associated with investing in foreign securities that are not typically associated with investing in U.S. companies. These risks include fluctuations in the exchange rates of foreign currencies that may affect the U.S. dollar value of a security, and the possibility of substantial price volatility as a result of political and economic instability in the foreign country. Other risks of investing in foreign securities include: less public information about issuers of securities, different securities regulation, different accounting, auditing and financial reporting standards and less liquidity in foreign markets than in U.S. markets.

Fund of Funds Risk. Because the Fund is a "fund of funds," its investment performance largely depends on the investment performance of the funds in which it invests. An investment in the Fund is subject to the risks associated with such funds. Therefore, there is a risk that the Fund may suffer losses due to the investment practices or operations of the funds in which it invests. To the extent that the Fund invests in one or more funds that concentrate in a particular type of security or specific industry, the Fund would be exposed to such specific securities' risks and be vulnerable to factors affecting that industry and may cause the Fund to be more volatile than other funds. The funds held by the Fund are not subject to the Fund's investment policies and restrictions. The Fund generally receives information regarding the portfolio holdings of such funds only when that information is made available to the public. The Fund cannot dictate how such funds invest their assets. The funds may invest their assets in securities and other instruments, and may use investment techniques and strategies, that are not described in this disclosure.

The Fund will pay indirectly a proportional share of the fees and expenses of the funds in which it invests (referred to herein as "acquired fund fees and expenses"), including their investment advisory and administration fees, in addition to its own fees and expenses. In addition, at times, certain segments of the market represented by the funds in which the Fund invests may be out of favor and underperform other segments.

Futures and Forward Contracts Risk. Futures contracts provide for the future sale by one party and purchase by another of a specific asset at a specific time and price (with or without delivery required). Futures contracts are standardized contracts traded on a recognized exchange. An option on a futures contract gives the purchaser the right, in exchange for a premium, to assume a position in a futures contract at a specified exercise price during the term of the option. Futures and forward contracts are subject to counterparty risk, meaning that the party with whom a Fund enters into the derivatives transaction (the clearinghouse or the broker holding the Fund's position for a futures contract or the counterparty for a forward contract) may experience a significant credit event and/or may be unwilling or unable to make timely settlement payments or otherwise honor its obligations.

High Yield Fixed-Income Securities (Junk Bonds) Risk. Investment in junk bonds entails a greater risk than an investment in higher-rated securities. Although junk bonds typically pay higher interest rates than investment-grade bonds, there is a greater likelihood that the company issuing the junk bond will default on interest and principal payments. In the event of an issuer's bankruptcy, claims of other creditors may have priority over the claims of junk bond holders, leaving few or no assets to repay them. Junk bonds are also more sensitive to adverse economic changes or individual corporate developments than higher quality bonds. During a period of adverse economic changes, including a period of rising interest rates, companies issuing junk bonds may be unable to make principal and interest payments.

Large-Capitalization Investing Risk. Large-capitalization stocks as a group could fall out of favor with the market, which may cause a Fund to underperform funds that focus on other types of stocks. In addition, larger, more established companies may be unable to respond quickly to new competitive challenges such as changes in technology and consumer preferences. Many larger companies also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

Liquidity Risk. Liquidity risk exists when particular investments are difficult to purchase or sell. The Fund's investments in illiquid securities may reduce the returns of the Fund because it may be unable to sell the illiquid securities at an advantageous time or price.

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Market Maker Risk. If the Fund has lower average daily trading volumes, it may rely on a small number of third-party market makers to provide a market for the purchase and sale of Fund Shares. Any trading halt or other problem relating to the trading activity of these market makers could result in a dramatic change in the spread between the Fund's net asset value and the price at which the Fund Shares are trading on the Exchange, which could result in a decrease in value of the Fund Shares. In addition, decisions by market makers or authorized participants to reduce their role or step away from these activities in times of market stress could inhibit the effectiveness of the arbitrage process in maintaining the relationship between the underlying values of the Fund's portfolio securities and the Fund's market price. This reduced effectiveness could result in Fund Shares trading at a discount to net asset value and also in greater than normal intra-day bid-ask spreads for Fund Shares.

Market Risk. The risk that the securities markets will increase or decrease in value is considered market risk and applies to any security. If there is a general decline in the stock or fixed-income market, it is possible your investment may lose value regardless of the individual results of the companies in which the Fund invests.

MLP Risk. Investments in securities of MLPs involve risks that differ from investments in common stock, including risks related to limited control and limited rights to vote on matters affecting the MLP, risks related to the potential conflicts of interest between the MLP and the MLP's general partners, cash flow risks, dilution risks and risks related to the general partners right to require unit holders to sell their common units at an undesirable time or price.

MLP Tax Risk. MLPs generally do not pay federal income tax at the partnership level. Rather, each partner is allocated a share of the partnerships' income, gains, losses, deductions and credits. A change in current tax law, or a change in the underlying business of an MLP, could result in an MLP being treated as a corporation, instead of a partnership, for federal income tax purposes, which would result in such MLP being required to pay income tax on its taxable income. This would have the effect of reducing the amount of cash available for distribution by the MLP, potentially reducing the value of the Fund's investment and consequently your investment in the Fund.

MLP Liquidity Risk. Although common units of MLPs trade on the NYSE, the NASDAQ and Amex, certain MLP securities trade less frequently than those of larger companies due to their smaller capitalization. As a result, the price of such MLPs may display abrupt and erratic movements at times. Additionally it may be more difficult for the Fund to buy and sell significant amounts of such securities without unfavorable impact on prevailing market process. As a result, these securities may be difficult to dispose of at a fair price when the Adviser desires to do so. This may adversely affect the Fund's ability to take advantage of other market opportunities or make dividend distributions.

Equity Securities of MLPs Risk. MLP common units, like other equity securities, can be affected by macro-economic and other factors affecting the stock market in general, expectations of interest rates, investor sentiment towards an issuer or certain market sector, changes in a particular issuer's financial condition, or unfavorable or unanticipated poor performance of a particular issuer (in the case of MLPs, generally measured in terms of distributable cash flow). Prices of common units of individual MLPs, like the prices other equity securities, also can be affected by fundamentals unique to the partnership or company, including earnings power and coverage ratios.

Municipal Securities Risk. The Fund may invest in closed-end funds and/or ETFs that hold municipal obligations. The values of municipal securities may be adversely affected by local political and economic conditions and developments. Adverse conditions in an industry significant to a local economy could have a correspondingly adverse effect on the financial condition of local issuers. Other factors that could affect municipal securities include a change in the local, state, or national economy, demographic factors, ecological or environmental concerns, statutory limitations on the issuer's ability to increase taxes, and other developments generally affecting the revenue of issuers (for example, legislation or court decisions reducing state aid to local governments or mandating additional services). This risk would be heightened to the extent that an underlying fund invests a substantial portion of its assets in bonds issued pursuant to similar projects (such as those relating to the education, health care, housing, transportation, or utilities industries), in industrial development bonds, or in particular types of municipal securities (such as general obligation bonds, private activity bonds or moral obligation bonds) that are particularly exposed to specific types of adverse economic, business or political events. Changes in a municipality's financial health may also make it difficult for the municipality to make interest and principal payments when due. The values of municipal securities that depend on a specific revenue source to fund their payment obligations may fluctuate as a result of actual or anticipated changes in the

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cash flows generated by the revenue source or changes in the priority of the municipal securities to receive the cash flows generated by the revenue source. Under some circumstances, municipal securities might not pay interest unless the state legislature or municipality authorizes money for that purpose. Municipal securities may be more susceptible to downgrades or defaults during recessions or similar periods of economic stress. In addition, since some municipal obligations may be secured or guaranteed by banks and other institutions, the risk to an underlying fund could increase if the banking or financial sector suffers an economic downturn and/or if the credit ratings of the institutions issuing the guarantee are downgraded or at risk of being downgraded by a national rating organization. Such a downward revision or risk of being downgraded may have an adverse effect on the market prices of the bonds and thus the value of an underlying fund's investments. In addition to being downgraded, an insolvent municipality may file for bankruptcy. The reorganization of a municipality's debts may significantly affect the rights of creditors and the value of the securities issued by the municipality and the value of an underlying fund's investments. In addition, income from municipal securities held by an underlying fund could be declared taxable because of, among other things, unfavorable changes in tax laws, adverse interpretations by the Internal Revenue Service or state tax authorities, or noncompliant conduct of an issuer or other obligated party. Loss of tax-exempt status may cause interest received and distributed to shareholders by an underlying fund to be taxable and may result in a significant decline in the values of such municipal securities. Due to the COVID-19 pandemic, the risks of the municipal securities market have been magnified. The costs associated with combating the pandemic and the negative impact on tax revenues has adversely affected the financial condition of many states and political subdivisions. These risks may also adversely affect several sectors of the municipal bond market, such as airports, toll roads, hospitals and colleges, among many others. The full impact of the COVID-19 pandemic on state and political subdivisions' ability to make payments on debt obligations is impossible to predict, but could negatively impact the value of bonds, the ability of state and political subdivisions to make payments when due and the performance of the Fund.

National Closed Market Trading Risk. To the extent that the underlying securities and/or other assets held by the Fund trade on non-U.S. exchanges or in non-U.S. markets that may be closed when the securities exchange on which Fund Shares trade is open, there are likely to be deviations between the current price of such an underlying security and the last quoted price for the underlying security (i.e., the Fund's quote from the closed non-U.S. market). The impact of a closed foreign market on the Fund is likely to be greater where a large portion of the Fund's underlying securities and/or other assets trade on that closed non-U.S. market or when the non-U.S. market is closed for unscheduled reasons. These deviations could result in premiums or discounts to the Fund's NAV that may be greater than those experienced by other ETFs.

New Fund Risk. The Fund is a recently organized investment company with a limited operating history. As a result, prospective investors have a limited track record or history on which to base their investment decision.

Non-Diversification Risk. The Fund is classified as "non-diversified" under the 1940 Act. As a result, the Fund is only limited as to the percentage of its assets which may be invested in the securities of any one issuer by the diversification requirements imposed by the Internal Revenue Code of 1986, as amended. The Fund may invest a relatively high percentage of its assets in a limited number of issuers. As a result, the Fund may be more susceptible to a single adverse economic or regulatory occurrence affecting one or more of these issuers, experience increased volatility and be highly invested in certain issuers.

Options Risk. There are significant differences between the securities and options markets that could result in an imperfect correlation among these markets, causing a given transaction not to achieve its objectives. The Fund's ability to utilize options successfully will depend on Calamos Advisors' ability to predict pertinent market movements, which cannot be assured.

The Fund's ability to close out its position as a purchaser or seller of an Options Clearing Corporation or exchange-listed put or call option is dependent, in part, upon the liquidity of the options market. If the Fund were unable to close out an option that it had purchased on a security, it would have to exercise the option to realize any profit or the option would expire and become worthless. If the Fund were unable to close out a covered call option that it had written on a security, it would not be able to sell the underlying security until the option expired. As the writer of a covered call option on a security, the Fund foregoes, during the option's life, the opportunity to profit from increases in the market value of the security covering the call option above the sum of the premium and the exercise price of the call. The hours of trading for listed options may not coincide with the hours during which the underlying financial instruments are traded. To the extent that the option markets close before the

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markets for the underlying financial instruments, significant price and rate movements can take place in the underlying markets that cannot be reflected in the option markets until the next trading day.

Unless the parties provide for it, there is no central clearing or guaranty function in an over-the-counter option. As a result, if the counterparty fails to make or take delivery of the security or other instrument underlying an over-the-counter option it has entered into with the Fund or fails to make a cash settlement payment due in accordance with the terms of that option, the Fund will lose any premium it paid for the option as well as any anticipated benefit of the transaction. Accordingly, Calamos Advisors must assess the creditworthiness of each such counterparty or any guarantor or credit enhancement of the counterparty's credit to determine the likelihood that the terms of the over-the-counter option will be satisfied.

The Fund may also purchase or write over-the-counter put or call options, which involves risks different from, and possibly greater than, the risks associated with exchange-listed put or call options. In some instances, over-the-counter put or call options may expose the Fund to the risk that a counterparty may be unable or unwilling to perform according to a contract, and that any deterioration in a counterparty's creditworthiness could adversely affect the instrument. In addition, the Fund may be exposed to a risk that losses may exceed the amount originally invested.

Other Investment Companies (including closed-end funds, ETFs, and BDCs) Risk. The Fund invests in the securities of other investment companies (including closed-end funds, ETFs and BDCs) consistent with the Fund's investment objective and the policies are permissible under the 1940 Act. Investments in the securities of other investment companies may involve duplication of advisory fees and certain other expenses. Additionally, if the investment company fails to achieve its investment objective, the value of the Fund's investment will decline, adversely affecting the Fund's performance. In addition, closed-end funds, ETF, and BDC shares potentially may trade at a discount or a premium and are subject to brokerage and other trading costs, which could result in greater expenses to the Fund. Whether the Fund will realize a gain or loss upon the sale of the such shares of closed-end funds, ETFs, and BDCs depends upon whether the market value of the shares at the time of sale is above or below the price the Fund paid, taking into account transaction costs for the shares, and is not directly dependent upon the NAV of the shares of such funds. Because the market value of the shares will be determined by factors such as the relative demand for and supply of the shares in the market, general market conditions and other factors, it cannot be predicted whether such shares will trade at, below or above NAV, or below or above the public offering price for the shares. Common Shares, as well as shares issued by the closed-end funds, do not assure dividend payments. Dividends are paid only when declared by the boards of directors of the closed-end funds, and the level of dividends may vary over time. If a closed-end fund reduces or eliminates the level of its regular dividends, this may reduce the level of dividends paid by the Fund, and may cause the market prices of the closed-end fund's shares to fall.

In accordance with Section 12(d)(1)(F) of the 1940 Act, on which the Fund intends to rely to invest in other investment companies, the Fund will be restricted by provisions of the 1940 Act that limit the amount the Fund can invest in any one investment company to 3% of the investment company's total outstanding stock. As a result, the Fund may hold a smaller position in an investment company than if it were not subject to this restriction. However, if the Adviser determines that it is in the Fund's best interest to exceed the 3% limit, it may rely on Rule 12d1-4 under the 1940 Act. Rule 12d1-4 would permit the Fund to invest in excess of the 3% limit subject to certain conditions, including that the Fund must enter into a "Fund of Funds Investment Agreement" with the acquired investment company setting forth the material terms of the arrangement. In addition, to comply with provisions of the 1940 Act, on any matter upon which investment company stockholders are solicited to vote, the Adviser will vote investment company shares in the same general proportion as shares held by other stockholders of the investment company (a practice known as "echo voting"). This could limit the Fund's ability to support or oppose investment company shareholder voting matters.

Portfolio Selection Risk. The value of your investment may decrease if the judgment of Calamos Advisors about the attractiveness, value or market trends affecting a particular security, issuer, industry, or sector or about market movements is incorrect.

Portfolio Turnover Risk. Engaging in active and frequent trading of securities may result in a higher than average level of capital gains and greater transaction costs to the Fund, including brokerage commissions or dealer mark-ups and other transaction costs on the sale and reinvestments of securities. Such sales may also result in the realization of capital gains,

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including short-term capital gains (which are taxed at ordinary income tax rates for federal income tax purposes, rather than at lower capital gains rates) and may adversely impact the Fund's performance. It is possible that the Fund engaging in active and frequent trading may be required to make significant distributions derived from taxable gains, regardless of the Fund's net longer term performance. The trading costs and tax effects associated with portfolio turnover will adversely affect the Fund's performance and lower the Fund's effective return for investors.

Premium-Discount Risk. The Fund Shares may trade above or below their net asset value ("NAV"). The market prices of Fund Shares will generally fluctuate in accordance with changes in NAV as well as the relative supply of, and demand for, Fund Shares on the Exchange. The trading price of Fund Shares may deviate significantly from NAV during periods of market volatility.

Secondary Market Trading Risk. Investors buying or selling Fund Shares in the secondary market will pay brokerage commissions or other charges imposed by brokers as determined by that broker. Brokerage commissions are often a fixed amount and may be a significant proportional cost for investors seeking to buy or sell relatively small amounts of Fund Shares. Although the Fund Shares are listed on the Exchange, there can be no assurance that an active or liquid trading market for them will develop or be maintained. In addition, trading in Fund Shares on the Exchange may be halted.

Sector Risk. To the extent the Fund invests a significant portion of its assets in a particular sector, a greater portion of the Fund's performance may be affected by the general business and economic conditions affecting that sector. Each sector may share economic risk with the broader market, however there may be economic risks specific to each sector. As a result, returns from those sectors may trail returns from the overall stock market and it is possible that the Fund may underperform the broader market, or experience greater volatility.

Short Sale Risk. Short sales involve risks. The Fund may incur a loss (without limit) as a result of a short sale if the market value of the borrowed security (i.e., the Fund's short position) increases between the date of the short sale and the date the Fund replaces the security. The Fund may be unable to repurchase the borrowed security at a particular time or at an acceptable price. The Fund might be unable to implement its strategy because of the lack of attractive short sale opportunities. If a convertible security used to cover a short position is called before conversion, the Fund may be required to purchase the security sold short at a price in the open market above the price at which the Fund had sold the security short.

Tax Risk. The Fund intends to elect and to qualify each year to be treated as a regulated investment company under Subchapter M of the Code. The federal income tax treatment of securities in which the Fund may invest may not be clear or may be subject to recharacterization by the Internal Revenue Service. It could be more difficult to comply with the tax requirements applicable to regulated investment companies if the tax characterization of investments or the tax treatment of the income from such investments were successfully challenged by the Internal Revenue Service. Any such failure to comply with the rules applicable to regulated investment companies could cause the Fund to fail to qualify as such. If the Fund does not qualify as a regulated investment company for any taxable year, and certain relief provisions are not available, the Fund's taxable income will be subject to tax at the Fund level and to a further tax at the shareholder level when such income is distributed.

Trading Issues Risk. Trading in Fund Shares on the Exchange may be halted due to market conditions or for reasons that, in the view of the Exchange, make trading in shares inadvisable. In addition, trading in Fund Shares on the Exchange is subject to trading halts caused by extraordinary market volatility pursuant to the Exchange's "circuit breaker" rules. There can be no assurance that the requirements of the Exchange necessary to maintain the listing of the Fund will continue to be met or will remain unchanged. The Fund may have difficulty maintaining its listing on the Exchange in the event the Fund's assets are small, the Fund does not have enough shareholders, or if the Fund is unable to proceed with creation and/or redemption orders.

The following are non-principal risks that generally apply to the Fund:

Cybersecurity Risk. Investment companies, such as the Fund, and their service providers are exposed to operational and information security risks resulting from cyberattacks, which may result in financial losses to the Fund and its shareholders. Cyber- attacks include, among other behaviors, stealing or corrupting data maintained online or digitally, denial of service

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attacks on websites, "ransomware" that renders systems inoperable until ransom is paid, the unauthorized release of confidential information, or various other forms of cybersecurity breaches. Cyber-attacks affecting the Fund, Calamos Advisors, custodian, transfer agent, distributor, administrator, intermediaries, trading counterparties, and other third-party service providers may adversely impact the Fund or the companies in which the Fund invests, causing the Fund's investments to lose value or to prevent a shareholder redemption or purchase from clearing in a timely manner.

Inflation Risk. The risk that the value of assets or income from the Fund's investments will be worth less in the future as inflation decreases the value of payments at future dates is considered inflation risk. As inflation increases, the value of the Fund's portfolio could decline. Inflation rates may change frequently and drastically as a result of various factors and the Fund's investments may not keep pace with inflation, which may result in losses to the Fund's investors or adversely affect the value of shareholders' investments in the Fund.

Investment Management Risk. Whether the Fund achieves its investment objective(s) is significantly impacted by whether Calamos Advisors is able to choose suitable investments for the Fund.

Market Disruption Risk. Certain events have a disruptive effect on securities markets, including but not limited to, terrorist attacks, war and other geopolitical events or catastrophes. Calamos Advisors cannot predict the effect of similar events in the future on the U.S. or foreign economies. Certain securities such as high yield and equity securities tend to be impacted more by these events than other types of securities in terms of price and volatility.

Operational Risk. The Fund is subject to risks arising from various operational factors, including, but not limited to, human error, processing and communication errors, errors of the Fund's service providers, counterparties or other third-parties, failed or inadequate processes and technology or systems failures. The Fund relies on third-parties for a range of services, including custody. Any delay or failure relating to engaging or maintaining such service providers may affect the Fund's ability to meet its investment objective. Although the Fund and the Adviser seek to reduce these operational risks through controls and procedures, there is no way to completely protect against such risks.

Recent Market Events. Since the 2008 financial crisis, financial markets throughout the world have experienced periods of increased volatility, depressed valuations, decreased liquidity and heightened uncertainty and turmoil. This turmoil resulted in unusual and extreme volatility in the equity and debt markets, in the prices of individual securities and in the world economy. Events that have contributed to these market conditions include, but are not limited to, major cybersecurity events, geopolitical events (such as wars (including Russia's military invasion of the Ukraine), terror attacks, natural or environmental disasters, country instability, and public health emergencies), measures to address budget deficits, downgrading of sovereign debt, dramatic changes in currency exchange rates, and public sentiment.

In addition, policy and legislative changes in the United States and in other countries are changing many aspects of financial regulation. The impact of these changes on the markets, and the practical implications for market participants, may not be fully known for some time. Widespread disease and virus epidemics and pandemics, such as the coronavirus outbreak, could likewise be highly disruptive, adversely affecting individual companies, sectors, industries, markets, currencies, interest and inflation rates, credit ratings, investor sentiment, and other factors affecting the value of the Fund's investments.

Portfolio security holdings disclosure

A description of the Fund's policies and procedures in connection with the disclosure of portfolio security holdings of the Fund is available in the Fund's SAI at www.calamos.com.

Fund Facts

Who manages the Fund?

Investment Adviser

The Fund is advised by Calamos Advisors LLC ("Calamos Advisors" or the "Adviser"), 2020 Calamos Court, Naperville, Illinois 60563. Calamos Advisors, an investment adviser registered with the SEC effective May 29, 1987, is a wholly owned subsidiary of Calamos Investments LLC ("CILLC"). CILLC's assets under management as of December 31, 2023, were $35 billion ($34 billion of which represented Calamos Advisors' assets under management). Calamos Asset Management, Inc. ("CAM") is the sole manager of CILLC. As of December 31, 2023, approximately 22% of the outstanding interests of CILLC was owned by CAM and the remaining approximately 78% of CILLC was owned by Calamos Partners LLC ("CPL") and John P. Calamos, Sr. CAM was owned by John P. Calamos, Sr. and John S. Koudounis, and CPL was owned by John S. Koudounis and Calamos Family Partners, Inc. ("CFP"). CFP was beneficially owned by members of the Calamos family, including John P. Calamos, Sr.

Subject to the overall authority of the Board of Trustees, Calamos Advisors provides continuous investment supervision and management to the Fund under a management agreement and also furnishes office space, equipment and management personnel. For these services, the Fund pays Calamos Advisors a fee based on its average daily net assets, which is accrued daily and paid on a monthly basis. The Fund will pay fees (before any reimbursement) under the management agreement in the following amounts as a percentage of its average net assets:

Out of this management fee, Calamos Advisors pays substantially all expenses of the Fund, including the cost of transfer agency, custody, fund administration, legal, audit and other service and license fees, except for distribution and service fees payable pursuant to a Rule 12b-1 plan, if any, acquired fund fees and expenses, brokerage commissions and other expenses connected with the execution of portfolio transactions, taxes, interest, and extraordinary expenses.

At a meeting held on September 26, 2023, the Board of Trustees approved the Investment Management Agreement for the Fund. A discussion regarding the basis for the Board's approval of the Investment Management Agreement on behalf of the Fund is included in the Fund's Form N-CSR for the fiscal year ended July 31, 2024.

Prior Related Performance of the Adviser

The performance information shown below represents the related performance of the Calamos CEF Income & Arbitrage Composite (the "Composite"). The Composite was created on February 1, 2021. From February 1, 2021 through January 31, 2024, the Composite consisted solely of a single separately managed account (the "Account") managed by Calamos Advisors, which, as of May 31, 2024, consisted of $1,545,713 of CILLC's own investment. From February 1, 2024 through May 31, 2024, the Composite consisted of the Account and the Fund. Thereafter, the Composite consisted solely of the Fund. The Composite has an investment objective, policies, strategies and restrictions that are substantially similar to the Fund. The Account and the Fund have been the only accounts or funds managed by the Adviser with an investment objective, policies, strategies and restrictions that are substantially similar to the Fund. The performance table below provides a summary of the performance of the Composite as of September 30, 2024, and compares the Composite's performance during the periods shown against the Fund's primary benchmark, the S-Network Composite Closed End Fund Index, a fund index designed to serve as a benchmark for closed-end funds listed in the US that principally engage in asset management processes seeking to produce taxable annual yield.

Except during the period from June 1, 2024 through September 30, 2024, the performance of the Composite does not represent the historical performance of the Fund and should not be considered a substitute for the Fund's performance or indicative of past or future performance of the Fund. Results may differ because of the fact that the Fund only has been part of the Composite since February 1, 2024 and because of differences in brokerage commissions, account expenses (including management fees), the size of positions taken in relation to account size and diversification of securities, timing of purchases and sales, and availability of cash for new investments, among other things. In addition, the Account was not subject to certain investment limitations or other restrictions imposed by the 1940 Act and the Internal Revenue Code which, if applicable, may have adversely affected the performance results of the Account and, accordingly, the Composite. Gross returns do not reflect

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the impact of investment advisory fees but do reflect the impact of trading expenses such as brokerage commissions, exchange fees and/or taxes, and bid-offer spreads from external brokers. Results include the reinvestment of net realized gains, interest and dividend income but do not reflect the impact of taxes on an investor. The results for different periods may vary.

The performance information below represents the actual performance of the Composite, shown gross (reflecting the actual acquired fund fees and expenses incurred by the Account during the period the Account was included in the Composite and reflecting actual acquired fund fees and expenses incurred by the Fund during the period the Fund was included in the Composite) and net of actual annual operating expenses payable by the Fund. The actual acquired fund fees and expenses incurred by the Account during the period it was included in the Composite was approximately 1.74%. Accordingly, the returns shown for the Composite during the period from February 1, 2021 through May 31, 2024 are higher than they would be if the Fund's actual acquired fees and expenses were used to calculate performance instead of the actual acquired fund fees and expenses incurred by the Account. The Fund's actual acquired fund fees and expenses are reflected in the Composite's performance for the period from June 1, 2024 through September 30, 2024. As shown in the Annual Fund Operating Expenses table in this Prospectus, the acquired fund fees and expenses that an investor may pay is 3.30% (based on the Fund's actual acquired fund fees and expenses from January 16, 2024 through July 31, 2024).

AVERAGE ANNUAL TOTAL RETURNS FOR THE PERIODS ENDED SEPTEMBER 30, 2024

Portfolio Managers

R. Matthew Freund. R. Matthew Freund joined Calamos Advisors in November 2016 as a Co-CIO, Head of Fixed Income Strategies, as well as a Senior Co-Portfolio Manager. Previously, he was SVP of Investment Portfolio Management and Chief Investment Officer at USAA Investments since 2010.

Shaheen Iqubal. Shaheen Iqubal joined Calamos Advisors in 2017 as Senior Vice President, Head of Quantitative Investments, Co-Head of Risk, and since January 2024 has been an Associate Portfolio Manager. Shaheen is responsible for oversight of our quantitative investment and risk management teams. Prior to joining the firm, Shaheen was executive director and senior quantitative analyst in the applied research group at UBS Asset Management.

The Fund's SAI provides additional information about each portfolio manager, including other accounts they manage, their ownership in the Calamos Family of Funds and their compensation.

Management Approach

Calamos Advisors employs a "team of teams" approach to portfolio management, led by the Global CIO and our CIO team consisting of 5 Co-CIOs with specialized areas of investment expertise. The Global CIO and Co-CIO team are responsible for oversight of investment team resources, investment processes, performance and risk. As heads of investment verticals, Co-CIOs manage investment team members and, along with Co- Portfolio Managers and Associate Portfolio Managers, have day-to-day portfolio oversight and construction responsibilities of their respective investment strategies. While investment research professionals within each Co-CIO's team are assigned specific strategy responsibilities, they also provide support to other investment team verticals, creating deeper insights across a wider range of investment strategies. The combination of specialized investment teams with cross team collaboration results in what we call our team of teams approach.

This team of teams approach is further reflected in the composition of Calamos Advisors' Investment Committee, made up of the Global CIO, the Co-CIO team, and the Global Head of Trading. Other members of the investment team participate in Investment Committee meetings in connection with specific investment related issues or topics as deemed appropriate.

Fund Facts

The structure and composition of the Investment Committee results in a number of benefits, as it:

•  Leads to broader perspective on investment decisions: multiple viewpoints and areas of expertise feed into consensus;

•  Promotes collaboration between teams; and

•  Functions as a think tank with the goal of identifying ways to outperform the market on a risk-adjusted basis.

The objectives of the Investment Committee are to:

•  Form the firm's top-down macro view, market direction, asset allocation, and sector/country positioning.

•  Establish firm-wide secular and cyclical themes for review.

•  Review firm-wide and portfolio risk metrics, recommending changes where appropriate.

•  Review firm-wide, portfolio and individual security liquidity constraints.

•  Evaluate firm-wide and portfolio investment performance.

•  Evaluate firm-wide and portfolio hedging policies and execution.

•  Evaluate enhancements to the overall investment process.

R. Matthew Freund is a Senior Co-Portfolio Manager of the Fund. Shaheen Iqubal is an Associate Portfolio Manager of the Fund. Senior Co-Portfolio Managers and Associate Portfolio Managers are collectively referred to within this registration statement as "Portfolio Managers".

How to Buy and Sell Shares

Fund Shares are listed for secondary trading on the Exchange under the symbol CCEF and individual Fund Shares may only be purchased and sold in the secondary market through a broker-dealer. The Exchange and secondary markets are closed on weekends and also are generally closed on the following holidays: New Year's Day, Dr. Martin Luther King, Jr. Day, Presidents' Day, Good Friday, Memorial Day (observed), Juneteenth, Independence Day, Labor Day, Thanksgiving Day and Christmas Day. The Exchange may close early on the business day before certain holidays and on the day after Thanksgiving Day. Exchange holiday schedules are subject to change without notice. If you buy or sell Fund Shares in the secondary market, you will pay the secondary market price for Fund Shares. In addition, you may incur customary brokerage commissions and charges and may pay some or all of the spread between the bid and the offered price in the secondary market on each leg of a round trip (purchase and sale) transaction.

The trading prices of Fund Shares will fluctuate continuously throughout trading hours based on market supply and demand rather than the relevant Fund's net asset value, which is calculated at the end of each business day. Fund Shares will trade on the Exchange at prices that may be above (i.e., at a premium) or below (i.e., at a discount), to varying degrees, the daily net asset value of Fund Shares. The trading prices of Fund Shares may deviate significantly from the Fund's net asset value during periods of market volatility. Given, however, that Fund Shares can be issued and redeemed daily in Creation Units, the Adviser believes that large discounts and premiums to net asset value should not be sustained over long periods.

Authorized Participants may acquire shares directly from the Fund, and Authorized Participants may tender their shares for redemption directly to the Fund, at NAV per share only in Creation Units. Purchases and redemptions directly with the Fund must follow the Fund's procedures, which are described in the SAI.

The Fund may liquidate and terminate at any time without shareholder approval.

Book Entry

Fund Shares are held in book-entry form, which means that no stock certificates are issued. The Depository Trust Company ("DTC") or its nominee is the record owner of all outstanding Shares of the Fund and is recognized as the owner of all Shares for all purposes.

Investors owning Fund Shares are beneficial owners as shown on the records of DTC or its participants. DTC serves as the securities depository for all Fund Shares. Participants in DTC include securities brokers and dealers, banks, trust companies, clearing corporations and other institutions that directly or indirectly maintain a custodial relationship with DTC. As a beneficial owner of Fund Shares, you are not entitled to receive physical delivery of stock certificates or to have Fund Shares registered in

Fund Facts

your name, and you are not considered a registered owner of Fund Shares. Therefore, to exercise any right as an owner of Fund Shares, you must rely upon the procedures of DTC and its participants. These procedures are the same as those that apply to any other securities that you hold in book entry or "street name" form.

Fund Share Trading Prices

The trading prices of Shares of the Fund on the Exchange may differ from the Fund's daily NAV. Market forces of supply and demand, economic conditions and other factors may affect the trading prices of Shares of the Fund.

The approximate value of Shares of the Fund, an amount representing on a per share basis the sum of the current market price of the cash or securities, as applicable, accepted by the Fund in exchange for Shares of the Fund and an estimated cash component, if any, is disseminated every 15 seconds throughout the trading day through the facilities of the Consolidated Tape Association. This approximate value should not be viewed as a "real-time" update of the NAV per Share of the Fund because the approximate value may not be calculated in the same manner as the NAV, which is computed once a day, generally at the end of the business day. The Fund is not involved in, or responsible for, the calculation or dissemination of the approximate value of the Fund Shares and the Fund does not make any warranty as to its accuracy.

Frequent Purchases and Redemptions of Fund Shares

Shares of the Fund may be purchased and redeemed directly from the Fund only in Creation Units by Authorized Participants. The vast majority of trading in Shares of the Fund occurs on the secondary market, and does not involve the Fund directly. In-kind purchases and redemptions of Creation Units by Authorized Participants and cash trades on the secondary market are unlikely to cause many of the harmful effects of frequent purchases and/or redemptions of Fund Shares. Cash purchases and/or redemptions of Creation Units, however, can result in disruption of portfolio management, dilution to the Fund and increased transaction costs, which could negatively impact the Fund's ability to achieve its investment objective, and may lead to the realization of capital gains. These consequences may increase as the frequency of cash purchases and redemptions of Creation Units by Authorized Participants increases. However, direct trading by Authorized Participants is critical to ensuring that Fund Shares trade at or close to NAV.

The Fund imposes no restrictions on the frequency of purchases and redemptions ("market timing"). To minimize these potential consequences of frequent purchases and redemptions of Fund Shares, the Fund employs fair valuation pricing, and imposes transaction fees on purchases and redemptions of Creation Units to cover the custodial and other costs the Fund incurs in effecting trades. In addition, the Adviser monitors trades by Authorized Participants for patterns of abusive trading and the Fund reserves the right to not accept orders from Authorized Participants that the Adviser has determined may be disruptive to the management of the Fund, or otherwise are not in the best interests of the Fund. For these reasons, the Board has not adopted policies and procedures with respect to frequent purchases and redemptions of Fund Shares. The Trust's policies and procedures regarding frequent purchases and redemptions may be modified by the Board of Trustees at any time.

The Trust's policies and procedures prohibit the practice of any officer or employee of the Trust, a Trust investment adviser (including any sub-adviser), the distributor, custodian, or transfer agent, or other affiliated person of the Trust placing orders to purchase or redeem shares of a series of the Trust after the designated time as of which the Fund calculates its NAV (i.e. "late trading").

Distribution and Service Plan

The Fund has adopted a distribution and service plan ("Plan") pursuant to Rule 12b-1 under the Investment Company Act. Under the Plan, the Fund is authorized to pay distribution fees to the Distributor and other firms that provide distribution and shareholder services ("Service Providers"). If a Service Provider provides such services, the Fund may pay fees at an annual rate not to exceed 0.25% of average daily net assets, pursuant to Rule 12b-1 under the Investment Company Act.

No distribution or service fees are currently paid by the Fund, however, and there are no current plans to impose these fees. In the event Rule 12b-1 fees are charged, over time they would increase the cost of an investment in the Fund because they would be paid on an ongoing basis.

Fund Facts

Fund Website and Disclosure of Portfolio Holdings

The Trust maintains a website for the Fund at www.calamos.com. Among other things, this website includes this Prospectus and the SAI, and will include the Fund's holdings, the Fund's last annual and semi-annual reports (when available), pricing information about Fund Shares trading on the Exchange, daily NAV calculations and a historical comparison of the trading prices to NAV.

Each day the Fund is open for business, the Trust publicly disseminates the Fund's full portfolio holdings as of the close of the previous day through its website at www.calamos.com. A description of the Trust's policies and procedures with respect to the disclosure of the Fund's portfolio holdings is available in the Fund's SAI.

Dividends, Other Distributions and Taxes

Fund Distributions

The Fund expects to declare and distribute its net investment income, if any, to shareholders as dividends monthly. The Fund may distribute such investment income more frequently, if necessary, in order to reduce or eliminate federal excise or income taxes on the Fund. The Fund expects to declare and distribute capital gains, if any, on an annual basis. The Fund typically earns dividends from stocks in which it invests. These amounts, net of expenses, are passed along to Fund shareholders as "income dividends." The Fund realizes capital gains or losses whenever it sells securities. Net long-term capital gains are distributed to shareholders as "capital gain dividends."

Brokers may make available to their customers who own Fund Shares the DTC book-entry dividend reinvestment service. To determine whether the dividend reinvestment service is available and whether there is a commission or other charge for using this service, consult your broker. Brokers may require Fund shareholders to adhere to specific procedures and timetables. If this service is available and used, dividend distributions of both income and net realized gains will be automatically reinvested in additional whole Fund Shares of the Fund purchased in the secondary market. Without this service, investors would receive their distributions in cash.

Taxes

As with any investment, you should consider how your investment in Fund Shares will be taxed. The tax information in this prospectus is provided only as general information. This section is current as of the date of this prospectus. Tax laws and interpretations change frequently, and these summaries do not describe all of the tax consequences to all taxpayers. For example, these summaries generally do not describe your situation if you are a corporation, a non-U.S. person, a broker-dealer, or other investor with special circumstances. However, with respect to certain tax issues, the summaries describe the general tax treatment of certain distributions made to corporations and non-U.S. persons. In addition, this section does not describe your state, local or non-U.S. tax consequences. You should consult your own tax advisor about the tax consequences of an investment in Fund Shares.

Fund distributions to you and the sale or redemption of your Fund Shares will have tax consequences to you. Such consequences may be different if you hold your Shares through a tax-exempt entity or tax-advantaged retirement account, such as an individual retirement account or 401(k) plan.

The Fund intends to elect to be treated, and intends to qualify each year, as a regulated investment company (a "RIC") under the Code. As a RIC, the Fund is generally not subject to corporate-level U.S. federal income tax on any net ordinary income or capital gains that are timely distributed to shareholders. However, the Fund's failure to qualify as a RIC or to meet minimum distribution requirements would result (if certain relief provisions were not available) in corporate-level taxation and, consequently, a reduction in amounts available for distribution to shareholders.

Taxes on Distributions

Distributions by the Fund generally are taxable to you as ordinary income or capital gains. Distributions are subject to federal income tax, whether received in cash or reinvested in additional Fund Shares or shares of another fund, and may be subject to state or local taxes. Distributions of the Fund's "investment company taxable income" generally will be taxable as ordinary income to the extent of the Fund's current or accumulated earnings and profits. Notwithstanding the foregoing, distributions

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that are attributable to "qualified dividends" received by the Fund may be eligible to be taxed at long-term capital gains rates, as long as the Fund and the shareholder meet certain holding period requirements.

Distributions of the Fund's net capital gain that are properly reported by the Fund as "capital gain dividends" will generally be taxable to you as long-term capital gains, currently at a maximum rate of 20%, regardless of your holding period in the Fund's Shares. Distributions in excess of the Fund's current and accumulated earnings and profits first will reduce your adjusted tax basis in your Fund Shares and, after the adjusted basis is reduced to zero, will constitute capital gain. Such capital gain will be long-term capital gain and thus, will be taxed at a maximum rate of 20%, if the distributions are attributable to Fund Shares that you have held for more than one year.

Certain non-corporate taxpayers will also be subject to a 3.8% U.S. federal Medicare contribution tax with respect to the lesser of (1) their "net investment income" or (2) the excess of their "modified adjusted gross income" over a threshold amount ($200,000 for single taxpayers and $250,000 for taxpayers who are married and filing jointly).

Corporate shareholders of the Fund are generally eligible for a dividends-received deduction with respect to ordinary income dividends (but not capital gain dividends) properly designated as eligible for such deduction by the Fund, as long as the Fund and the corporate shareholder meet certain holding period and other requirements.

Under a dividend reinvestment service, you may have the option to have all cash distributions automatically reinvested in additional Fund Shares. Any distributions reinvested under such a service will nevertheless be taxable to you as described above.

You will have an adjusted basis in the additional Fund Shares purchased through such a reinvestment service equal to the amount of the reinvested distribution plus the amount of any fees charged for the transaction. The additional Fund Shares will have a holding period commencing on the day following the day on which they are credited to your account.

A distribution will reduce the Fund's NAV per Share and generally will be taxable to you as ordinary income or capital gain even if it is paid from income or gains earned by the Fund before you invested in the Fund. From an investment standpoint, this constitutes a return of capital. However, from a tax standpoint, it constitutes taxable income. In general, distributions are subject to federal income tax as of the date of payment. However, distributions paid in January will be treated as paid on December 31 of the prior year if they were declared and payable to shareholders of record on a date in October, November or December of the prior year.

The Fund's investments in underlying closed-end funds, ETFs, and BDCs could affect the amount, timing and character of distributions from the fund, and therefore, may increase the amount of taxes payable by shareholders. In addition, the Fund's investments in certain debt instruments could cause the Fund to recognize taxable income in excess of the cash generated by such investments, which may require the Fund to dispose of other investments in order to make required distributions.

The Fund's transactions in derivatives, as well as its hedging, short sale, securities loan or similar transactions, if any, may be subject to one or more special tax rules. These rules may affect whether gains and losses recognized by the Fund are treated as ordinary or capital, accelerate the recognition of income or gains to the Fund, defer losses to the Fund, and cause adjustments in the holding periods of the Fund's securities, thereby affecting whether capital gains and losses are treated as short-term or long-term. These rules could therefore affect the amount, timing and/or character of distributions to shareholders and thus taxes payable by shareholders.

You may be subject to federal back-up withholding tax, if you do not provide the Fund with a taxpayer identification number (for an individual, a social security number) and make other required certifications, or the Internal Revenue Service informs the Fund that your tax identification number is incorrect. Backup withholding is not an additional tax. You may claim the amount withheld as a credit on your federal income tax return, provided you furnish the appropriate information to the Internal Revenue Service.

Taxes When Shares are Sold

Any capital gain or loss realized upon a sale of Fund Shares is generally treated as long-term capital gain or loss if you have held the Fund Shares for more than one year and as short-term capital gain or loss if you have held the Fund Shares for one year or less. The ability to deduct capital losses realized on a sale of Fund Shares may be limited.

Fund Facts

Taxes on Purchase and Redemption of Creation Units

An Authorized Participant that exchanges equity securities for Creation Units will generally recognize a gain or a loss on the exchange. Any such gain or loss will be equal to the difference between the market value of the Creation Units at the time of the exchange, plus (or minus) the cash amount received (or paid), and such Authorized Participant's aggregate basis in the securities surrendered. A person who redeems Creation Units for equity securities will generally recognize a gain or loss equal to the difference between the aggregate market value of the securities received, plus (or minus) any cash received (or paid), and such person's basis in the Creation Units redeemed. The Internal Revenue Service, however, may assert that a loss realized upon an exchange of securities for Creation Units cannot be deducted currently under the rules governing "wash sales," or on the basis that there has been no significant change in the Authorized Participant's economic position with respect to such Creation Units. Persons exchanging securities should consult their own tax advisor with respect to the applicability of the wash sale rules and the availability and timing of a deduction for any loss. In addition, when a regulated investment company redeems a shareholder in kind, the regulated investment company generally is not required to recognize taxable gains in respect of the portfolio securities it distributes to the redeeming shareholder. However, the Fund may be required to recognize taxable gain on the distribution of certain securities, and the Internal Revenue Service may assert that the Fund must recognize taxable gain in respect of certain other securities that the Fund distributes to a shareholder in exchange for Creation Units, which may increase the amount of taxable gains that the Fund would otherwise be required to distribute in order to maintain its qualification as a regulated investment company and avoid a Fund-level tax.

Any capital gain or loss realized upon a redemption of Creation Units is generally treated as long-term capital gain or loss if the Creation Units have been held for more than one year and as short-term capital gain or loss if the Creation Units have been held for one year or less. If you purchase or redeem Creation Units, you will be sent a confirmation statement showing how many Fund Shares you purchased or sold and at what price.

Treatment of Fund Expenses

Expenses incurred and deducted by the Fund will generally not be treated as income taxable to you.

Non-U.S. Taxes

Income and proceeds received by the Fund from sources within foreign countries may be subject to withholding and other taxes imposed by such countries, which would reduce the Fund's return on investments in such countries. Tax treaties between certain countries and the U.S. may reduce or eliminate such taxes. Shareholders generally will not be entitled separately to claim a credit or deduction in respect of non-U.S. taxes paid or treated as paid by the Fund. In addition, the Fund's investments in foreign securities or foreign currencies may increase or accelerate the Fund's recognition of ordinary income and may affect the timing or amount of the Fund's distributions.

Non-U.S. Investors

If you are a non-U.S. investor (i.e., an investor other than a U.S. citizen or resident or a U.S. corporation, partnership, estate or trust), you should be aware that, generally, subject to applicable tax treaties, distributions from the Fund will be characterized as dividends for U.S. federal income tax purposes (other than dividends which the Fund properly reports as capital gain dividends) and will be subject to U.S. federal income taxes, including withholding taxes, subject to certain exceptions described below. However, distributions received by a non-U.S. investor from the Fund that are properly reported by the Fund as capital gain dividends may not be subject to U.S. federal income taxes, including withholding taxes, provided that the Fund makes certain elections and certain other conditions are met. Distributions from the Fund that are properly reported by the Fund as an interest-related dividend attributable to certain interest income received by the Fund or as a short-term capital gain dividend attributable to certain net short-term capital gain income received by the Fund may not be subject to U.S. federal income taxes, including withholding taxes when received by certain non-U.S. investors, provided that the Fund makes certain elections and certain other conditions are met.

Distributions may be subject to a U.S. withholding tax of 30% in the case of distributions to (i) certain non-U.S. financial institutions that have not entered into an agreement with the U.S. Treasury to collect and disclose certain information and are not resident in a jurisdiction that has entered into such an agreement with the U.S. Treasury and (ii) certain other non-U.S. entities that do not provide certain certifications and information about the entity's U.S. owners. The Internal Revenue Service

Fund Facts

and the Department of Treasury have issued proposed regulations providing that these withholding rules will not be applicable to the gross proceeds of share redemptions or capital gains dividends that the Fund pays.

Investments in Certain Non-U.S. Corporations

If the Fund holds an equity interest in any "passive foreign investment companies" ("PFICs"), which are generally certain non-U.S. corporations that receive at least 75% of their annual gross income from passive sources (such as interest, dividends, certain rents and royalties or capital gains) or that hold at least 50% of their assets in investments producing such passive income, the Fund could be subject to U.S. federal income tax and additional interest charges on gains and certain distributions with respect to those equity interests, even if all the income or gain is timely distributed to its shareholders. The Fund will not be able to pass through to its shareholders any credit or deduction for such taxes. The Fund may be able to make an election that could ameliorate these adverse tax consequences. For instance, the Fund may elect to mark the gains (and to a limited extent losses) in such holdings "to the market" as though it had sold (and, solely for purposes of this mark-to-market election, repurchased) its holdings in those PFICs on the last day of the Fund's taxable year. If the Fund were to make a mark-to-market election, it would recognize as ordinary income any increase in the value of such PFIC shares, and as ordinary loss any decrease in such value to the extent it did not exceed prior increases included in income. Under this election, the Fund might be required to recognize in a year income in excess of its distributions from PFICs and its proceeds from dispositions of PFIC stock during that year, and such income would nevertheless be subject to the distribution requirement and would be taken into account for purposes of the 4% excise tax that may be imposed on the undistributed income of a RIC. Dividends paid by PFICs are not treated as qualified dividend income.

Other Tax Matters

The foregoing is only a summary of certain federal income tax considerations of investing in the Fund under current law, which is subject to change in the future. Shareholders who are not U.S. persons within the meaning of the Code, such as non-resident aliens, foreign trusts or estates, or foreign corporations or partnerships may be subject to different U.S. federal income tax treatment.

You may also be subject to state and local taxes on distributions paid by the Fund, and sales and redemptions of Fund Shares. You should consult your tax advisor for further information regarding federal, state, local and/or foreign tax consequences relevant to your specific tax situation. More information about taxes can be found in the Fund's SAI.

Net Asset Value

The NAV of shares is determined at the close of regular trading on the New York Stock Exchange (normally 4:00 p.m. Eastern Time) on each day the New York Stock Exchange ("NYSE") is open. NAV is computed by determining the aggregate market value of all assets of the Fund, less its liabilities, divided by the total number of shares outstanding ((assets-liabilities)/number of shares = NAV). The NYSE is closed on weekends and New Year's Day, Martin Luther King, Jr. Day, Presidents' Day, Good Friday, Memorial Day, Juneteenth National Independence Day, Independence Day, Labor Day, Thanksgiving Day and Christmas Day. The NAV takes into account the expenses and fees of the Fund, including management fees, which are accrued daily. The determination of NAV for the Fund for a particular day is applicable to all applications for the purchase of shares, as well as all requests for the redemption of shares, received by the Fund (or an authorized broker or agent, or its authorized designee) before the close of trading on the NYSE on that day.

Generally, securities traded or dealt in upon one or more securities exchanges (whether domestic or foreign) for which market quotations are readily available and not subject to restrictions against resale shall be valued at the last quoted sales price on the primary exchange or, in the absence of a sale on the primary exchange, at the mean between the current bid and ask prices on such exchange. Securities primarily traded in the National Association of Securities Dealers' Automated Quotation System ("NASDAQ") National Market System for which market quotations are readily available shall be valued using the NASDAQ official closing price. Securities that are not traded or dealt in any securities exchange (whether domestic or foreign) and for which over-the-counter market quotations are readily available generally shall be valued at the last sale price or, in the absence of a sale, at the mean between the current bid and ask price on such over-the-counter market. Debt securities not traded on an exchange may be valued at prices supplied by a pricing agent(s) based on broker or dealer supplied valuations or matrix pricing, a method of valuing securities by reference to the value of other securities with similar characteristics, such as rating,

Fund Facts

interest rate and maturity. Futures, swaps and options contracts listed for trading on a futures or options exchange or board of trade for which market quotations are generally available are valued at the last quoted sale price, or, in the absence of a sale, at the mean of the last bid and ask price. Total return swaps on exchange-listed securities are valued at the last quoted sale price, or, in the absence of a sale, at the mean of the last bid and ask price.

Securities held by the Fund are valued in accordance with policies and procedures established by the Adviser pursuant to Rule 2a-5 under the Investment Company Act of 1940 ("1940 Act") and approved by and subject to the oversight of the Board of Trustees ("Valuation Procedures"). If market quotations are not readily available, securities or other assets will be valued at their fair value as determined in good faith by the Adviser in accordance with procedures approved by the Board and evaluated by the Board as to the reliability of the fair value method used. In these cases, the Fund's NAV will reflect certain portfolio securities' fair values rather than their market prices. Fair value pricing involves subjective judgments, and it is possible that the fair value determined for a security or other asset may be materially different than the value that could be realized upon the sale of that security or other asset. The fair value prices can differ from market prices. The Board of Trustees has designated Calamos Advisors as "valuation designee" for the Fund. The valuation designee is responsible for determining the value of the Fund's investments. The designee may also enlist third party consultants such as an audit firm or financial officer of a security issuer on an as-needed basis to assist in determining a security-specific fair value. The Board reviews and ratifies the execution of this process and the resultant fair value prices at least quarterly to assure the process produces reliable results.

The Fund may use independent pricing services to assist in calculating the value of the Fund's securities or other assets.

With respect to any portion of the Fund's assets that are invested in one or more open-end management investment companies registered under the 1940 Act, the Fund's net asset value is calculated based upon the net asset values of those open-end management investment companies, and the prospectuses for these companies explain the circumstances under which those companies will use fair value pricing and the effects of using fair value pricing.

Fund Service Providers

State Street Bank and Trust Company ("State Street"), located at One Congress Street, Suite 1, Boston, Massachusetts 02114-2016, serves as the Fund's administrator, custodian, fund accounting and financial accounting agent, and transfer agent.

Calamos Financial Services LLC ("CFS"), located at 2020 Calamos Court, Naperville, Illinois 60563, serves as the distributor of Creation Units for the Fund on an agency basis. The Distributor does not maintain a secondary market in Fund Shares.

Ropes & Gray LLP, located at 191 North Wacker Drive, 32^nd​ Floor, Chicago, IL 60606, serves as legal counsel to the Trust.

Premium/Discount Information

Information showing the number of days the market price of the Fund Shares was greater (at a premium) and less (at a discount) than the Fund's NAV for the most recently completed calendar year, and the most recently completed calendar quarters since that year (or the life of the Fund, if shorter), is available at www.calamos.com.

Investments by Other Investment Companies

Section 12(d)(1) of the 1940 Act restricts investments by investment companies in the securities of other investment companies, including Fund Shares. Rule 12d1-4 under the 1940 Act permits investment companies ("acquiring funds") to invest in other investment companies ("acquired funds") beyond the limits of Section 12(d)(1), subject to certain terms and conditions. However, because more than 10% of the Fund's total assets are invested in securities of closed-end funds, ETFs, and BDCs, other investment companies are not permitted to rely on Rule 12d1-4 to invest in the Fund in excess of the limits of Section 12(d)(1). To this end, Rule 12d1-4 relief from Section 12(d)(1) is not available for investments in the Fund, since this Fund operates as a "fund of funds."

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Financial Highlights

The financial highlights table is intended to help you understand the Fund's financial performance for the period of January 16, 2024 (commencement of operations) through July 31, 2024. Certain information reflects financial results for a single Fund share. The total returns in the table represent the rate that an investor would have earned (or lost) on an investment in the Fund (assuming reinvestment of all dividends and distributions). This information has been audited by Deloitte & Touche LLP, whose report, along with the Fund's financial statements, are included in the SAI, which is available upon request.

FINANCIAL HIGHLIGHTS

Selected data for a share outstanding throughout the period was as follows:

  •  Commencement of operations.

  (a)  Net investment income (loss) allocated based on average shares method.

  (b)  Distribution for annual periods determined in accordance with federal income tax regulations.

  (c)  Total return measures net investment income (loss) and capital gain or loss from portfolio investments assuming reinvestment of dividends and capital gains distributions. Total return is not annualized for periods that are less than a full year and does not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

  (d)  Annualized.

  (e)  The Fund invests in other funds and indirectly bears its proportionate shares of fees and expenses incurred by the underlying funds in which the Fund is invested. This ratio does not include these indirect fees and expenses.

  (f)  Not annualized.

  (g)  Portfolio turnover rate excludes securities received or delivered from in-kind processing of creations or redemptions.

Other Information

Continuous Offering

The method by which Creation Units of Fund Shares are created and traded may raise certain issues under applicable securities laws. Because new Creation Units of Fund Shares are issued and sold by the Fund on an ongoing basis, a "distribution," as such term is used in the Securities Act of 1933, as amended (the "Securities Act"), may occur at any point. Broker-dealers and other persons are cautioned that some activities on their part may, depending on the circumstances, result in their being deemed participants in a distribution in a manner which could render them statutory underwriters and subject them to the prospectus delivery requirements and liability provisions of the Securities Act. For example, a broker-dealer firm or its client may be deemed a statutory underwriter if it takes Creation Units after placing an order with the Distributor, breaks them down into constituent Fund Shares and sells the Fund Shares directly to customers or if it chooses to couple the creation of a supply of new Fund Shares with an active selling effort involving solicitation of secondary market demand for Fund Shares. A determination of whether one is an underwriter for purposes of the Securities Act must take into account all the facts and circumstances pertaining to the activities of the broker-dealer or its client in the particular case, and the examples mentioned above should not be considered a complete description of all the activities that could lead to a characterization as an underwriter.

Broker-dealer firms should also note that dealers who are not "underwriters" but are effecting transactions in Fund Shares, whether or not participating in the distribution of Fund Shares, are generally required to deliver a prospectus. This is because the prospectus delivery exemption in Section 4(3) of the Securities Act is not available in respect of such transactions as a result of Section 24(d) of the Investment Company Act of 1940, as amended (the "Investment Company Act"). As a result, broker-dealer firms should note that dealers who are not "underwriters" but are participating in a distribution (as contrasted with engaging in ordinary secondary market transactions) and thus dealing with the Fund Shares that are part of an overallotment within the meaning of Section 4(3)(C) of the Securities Act, will be unable to take advantage of the prospectus delivery exemption provided by Section 4(3) of the Securities Act. For delivery of prospectuses to exchange members, the prospectus delivery mechanism of Rule 153 under the Securities Act is only available with respect to transactions on a national exchange.

Summary of Certain Provisions of the Second Amended and Restated Trust Instrument

The summary below is a synopsis of certain provisions contained in the Trust's Second Amended and Restated Trust Instrument (the "Trust Instrument"). Shareholders should refer to the Trust Instrument for further information. Defined terms have the meanings contained in the Trust Instrument.

Derivative Actions

The Second Amended and Restated Trust Instrument (the "Trust Instrument") requires, within Section 9 of Article IV, that before bringing any derivative action on behalf of the Fund, Shareholders must have made a written demand to the Board of Trustees requesting that they cause the Trust or affected Series or Class, as applicable, to file the action itself.

In order to warrant consideration, any such written demand must include at least the following:

(1)  a detailed description of the action or failure to act complained of and the facts upon which each such allegation is made;

(2)  a statement to the effect that the complaining Shareholders believe that they will fairly and adequately represent the interests of similarly situated Shareholders in enforcing the right of the Trust or the affected Series or Class, as applicable and an explanation of why the complaining Shareholders believe that to be the case;

(3)  a certification that the following requirements have been met, as well as information reasonably designed to allow the Trustees to verify that certification:

(a)  each complaining Shareholder was a Shareholder of the Trust or the affected Series or Class, as applicable, at the time of the action or failure to act complained of, or acquired the Shares afterwards by operation of law from a Person who was a Shareholder at that time; and

(b)  each complaining Shareholder was a Shareholder of the Trust or the affected Series or Class, as applicable, as of the time the demand required by Section 9 of Article IV was made; and

Other Information

(4)  a certification that each complaining Shareholder will be a Shareholder of the Trust or the affected Series or Class, as applicable as of the commencement of the derivative action.

The Trust Instrument further provides that at least 10% of the Shareholders of the Trust or the affected Series or Class, as applicable, must join in bringing the derivative action. This provision does not apply to claims brought under the federal securities laws.

The Trust Instrument also provides that a copy of the derivative complaint must be served on the Trust, assuming the requirements described above have already been met and the derivative action has not been barred as further described in the Trust Instrument.

Forum and Waiver of Jury Trial

Section 10 of Article X of the Trust Instrument outlines which shareholder actions must be brought in state court and which must be brought in federal court. This section states in particular that, unless the Trust consents in writing to the selection of an alternative forum, the Federal District Courts of the United States of America shall be the sole and exclusive forum for the resolution of any complaint asserting a cause of action arising under any federal securities law. This provision may increase costs for a shareholder to bring a claim or may limit a shareholder's ability to bring a claim in a judicial forum that they find more convenient or favorable. While the enforceability of the exclusive forum provisions may be challenged, this section also provides that if any provisions of Section 10 shall be held to be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining portions will still apply.

Section 10 of Article X of the Trust Instrument also states that shareholders and all other such persons bringing any such suit, action, or proceeding in the Superior Court in the State of Delaware waive the right to a trial by jury to the fullest extent permitted by law.

For more detailed information on the Fund, several additional sources of information are available to you. The Fund's SAI, incorporated by reference into this prospectus, contains detailed information on the Fund's policies and operation. Additional information about the Fund's investments is available in the annual and semi-annual reports to shareholders. In the Fund's annual reports, you will find a discussion of the market conditions and investment strategies that significantly impacted the Fund's performance during the last fiscal year. The Fund's most recent SAI, annual or semi-annual reports and certain other information are available free of charge by calling the Fund at (866) 363-9219, on the Fund's website at www.calamos.com or through your financial advisor. Shareholders may call the toll-free number above with any inquiries.

You may obtain this and other information regarding the Fund, including the SAI and Codes of Ethics adopted by the Adviser, Distributor and the Trust, directly from the SEC. Information on the SEC's website is free of charge. Visit the SEC's on-line EDGAR database at http://www.sec.gov. You may also request information regarding the Fund by sending a request (along with a duplication fee) to the SEC by sending an electronic request to [email protected].

Calamos CEF Income &
Arbitrage ETF

2020 Calamos Court
Naperville, IL 60563-2787
866.363.9219

www.calamos.com

SEC File #333-191151
#811-22887

CCEFSTAPRO 120224

Calamos Alternative Nasdaq^®​ & Bond ETF
(NASDAQ—CANQ)

Prospectus December 2, 2024

Calamos Alternative Nasdaq^®​ & Bond ETF (the "Fund") is a series of the Calamos ETF Trust (the "Trust") and an exchange-traded fund ("ETF"). The Fund lists and principally trades its shares on The Nasdaq Stock Market LLC ("NASDAQ" or the "Exchange").

The U.S. Securities and Exchange Commission ("SEC") has not approved or disapproved these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Table of Contents

Calamos Alternative Nasdaq^®​ & Bond ETF

Investment Objective

Fees and Expenses of the Fund

Annual Fund Operating Expenses (ongoing expenses that you pay each year as a percentage of the value of your investments):

Example

Portfolio Turnover

Principal Investment Strategies

Calamos Alternative Nasdaq^®​ & Bond ETF

Principal Risks

An investment in the Fund is subject to risks, and you could lose money on your investment in the Fund. There can be no assurance that the Fund will achieve its investment objective. You should not consider investing in the Fund if your investment objective differs from the Fund's investment objective or if you are not willing to accept the principal risks associated with an investment in the Fund. The risks associated with an investment in the Fund can increase during times of significant market volatility. Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The principal risks are presented in alphabetical order to facilitate

Calamos Alternative Nasdaq^®​ & Bond ETF

finding particular risks and comparing them with other funds. Each risk summarized below is considered a "principal risk" of investing in the Fund, regardless of the order in which it appears. The principal risks of investing in the Fund include:

•  Authorized Participant Concentration Risk — Only an Authorized Participant may engage in creation or redemption transactions directly with the Fund, and none of those Authorized Participants is obligated to engage in creation and/or redemption transactions. The Fund has a limited number of institutions that may act as Authorized Participants on an agency basis (i.e., on behalf of other market participants). To the extent that Authorized Participants exit the business or are not able or willing to proceed with creation or redemption orders with respect to the Fund and no other Authorized Participant is able to step forward to create or redeem, Fund Shares may be more likely to trade at a premium or discount to NAV and possibly face trading halts or delisting. Authorized Participant concentration risk may be heightened for ETFs, such as the Fund, that invest in securities issued by non-U.S. issuers or other securities or instruments that have lower trading volumes.

•  Costs of Buying and Selling Fund Shares — Due to the costs of buying or selling Fund Shares, including brokerage commissions imposed by brokers and bid/ask spreads, frequent trading of Fund Shares may significantly reduce investment results and an investment in Fund Shares may not be advisable for investors who anticipate regularly making small investments.

•  Debt Securities Risk — Debt securities are subject to various risks, including interest rate risk, credit risk and default risk.

•  Interest Rate Risk — The value of debt securities generally decreases in periods when interest rates are rising. In addition, interest rate changes typically have a greater effect on prices of longer-term debt securities than shorter term debt securities. Changes in interest rates by the Federal Reserve Board, and other events affecting fixed-income markets, may subject a Fund to heightened interest rate risk as a result of a rise in interest rates.

•  Credit Risk — A debt security could deteriorate in quality to such an extent that its rating is downgraded or its market value declines relative to comparable securities. Changes in actual or perceived creditworthiness may occur quickly. If the Fund holds securities that have been downgraded, or that default on payment, the Fund's performance could be negatively affected.

•  Default Risk — A company that issues a debt security may be unable to fulfill its obligation to repay principal and interest. The lower a bond is rated, the greater its default risk. To the extent the Fund holds securities that have been downgraded, or that default on payment, its performance could be negatively affected.

•  Equity Securities Risk — The securities markets are volatile, and the market prices of the Fund's securities may decline generally. The price of equity securities fluctuates based on changes in a company's financial condition and overall market and economic conditions. If the market prices of the securities owned by the Fund fall, the value of your investment in the Fund will decline.

•  Emerging Markets Risk — The Fund may invest in emerging markets. Emerging markets are markets of countries in the initial stages of industrialization and generally have low per capita income. Foreign (non-U.S.) companies are those that either maintain their principal place of business outside of the United States, have their securities principally traded on non-U.S. exchanges or were formed under the laws of non-U.S. countries. Foreign companies may include companies doing business in the United States but meet the general criteria of a foreign company described above. Certain emerging markets are sometimes referred to as "frontier markets." Frontier markets are the least advanced capital markets in the developing world. Frontier markets are countries with investable stock markets that are less established than those in the emerging markets.

•  ETF Risk — The Fund's investment in shares of ETFs subjects it to the risks of owning the securities underlying the ETF, as well as the same structural risks faced by an investor purchasing shares of the Fund, including authorized participant concentration risk, market maker risk, premium-discount risk and trading issues risk. As a shareholder in another ETF, the Fund bears its proportionate share of the ETF's expenses, subjecting Fund shareholders to duplicative expenses.

•  FLEX Options Risk — The Fund may invest in FLEX Options issued and guaranteed for settlement by The Options Clearing Corporation ("OCC"). FLEX Options are customized option contracts that trade on an exchange but provide investors with the ability to customize key contract terms like strike price, style and expiration date while achieving price

Calamos Alternative Nasdaq^®​ & Bond ETF

discovery in competitive, transparent auctions markets and avoiding the counterparty exposure of over-the-counter options positions. Like traditional exchange-traded options, FLEX Options are guaranteed for settlement by the OCC, a market clearinghouse that guarantees performance by counterparties to certain derivatives contracts. The Fund bears the risk that the OCC will be unable or unwilling to perform its obligations under the FLEX Options contracts. Additionally, FLEX Options may be illiquid, and in such cases, the Fund may have difficulty closing out certain FLEX Options positions at desired times and prices. The FLEX Options held by the Fund will be exercisable at the strike price only on their expiration date. Prior to the expiration date, the value of the FLEX Options will be determined based upon market quotations or using other recognized pricing methods. The value of the FLEX Options prior to the expiration date may vary because of related factors other than the value of the reference asset. Factors that may influence the value of the FLEX Options, other than gains or losses in the reference asset, may include interest rate changes, changing supply and demand, decreased liquidity of the FLEX Options and changing volatility levels of the reference asset. In connection with the creation and redemption of Fund Shares, to the extent market participants are not willing or able to enter into FLEX Option transactions with the Fund at prices that reflect the market price of the Fund Shares, the Fund's net asset value ("NAV") and, in turn the share price of the Fund, could be negatively impacted. The Fund may experience substantial downside from specific FLEX Option positions and certain FLEX Option positions may expire worthless.

•  Foreign Securities Risk — Risks associated with investing in foreign securities include fluctuations in the exchange rates of foreign currencies that may affect the U.S. dollar value of a security, the possibility of substantial price volatility as a result of political and economic instability in the foreign country, less public information about issuers of securities, different securities regulation, different accounting, auditing and financial reporting standards and less liquidity than in U.S. markets.

•  High Yield Risk — High yield securities and unrated securities of similar credit quality (commonly known as "junk bonds") are subject to greater levels of credit and liquidity risks. High yield securities are considered primarily speculative with respect to the issuer's continuing ability to make principal and interest payments.

•  Large-Capitalization Investing Risk — Large-capitalization stocks as a group could fall out of favor with the market, which may cause a Fund to underperform funds that focus on other types of stocks. In addition, larger, more established companies may be unable to respond quickly to new competitive challenges such as changes in technology and consumer preferences. Many larger companies also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

•  LEAPS Options Risk — The Fund's investments in options contracts may include long-term equity anticipation securities known as LEAPS Options. LEAPS Options are long-term exchange-traded call options that allow holders the opportunity to participate in the underlying securities' appreciation in excess of a specified strike price without receiving payments equivalent to any cash dividends declared on the underlying securities. A holder of a LEAPS Option will be entitled to receive a specified number of shares of the underlying stock upon payment of the exercise price, and therefore the LEAPS Option will be exercisable at any time the price of the underlying stock is above the strike price. However, if at expiration the price of the underlying stock is at or below the strike price, the LEAPS Option will expire and be worthless. The Fund purchases call option contracts. By purchasing call option contracts, the Fund purchases the right (but not the obligation) to purchase the reference asset at a pre-determined price (the "strike price") in exchange for a premium to the seller.

•  Liquidity Risk — FLEX Options — In the event that trading in the underlying FLEX Options is limited or absent, the value of the Fund's FLEX Options may decrease. There is no guarantee that a liquid secondary trading market will exist for the FLEX Options. The trading in FLEX Options may be less deep and liquid than the market for certain other securities, including certain non-customized option contracts. In a less liquid market for the FLEX Options, terminating the FLEX Options may require the payment of a premium or acceptance of a discounted price and may take longer to complete. Additionally, the liquidation of a large number of FLEX Options may more significantly impact the price in a less liquid market. Further, the Fund requires a sufficient number of participants to facilitate the purchase and sale of options on an exchange to provide liquidity to the Fund for its FLEX Option positions. A less liquid trading market may adversely impact the value of the FLEX Options and the value of your investment.

Calamos Alternative Nasdaq^®​ & Bond ETF

•  Liquidity Risk — LEAPS Options — In the event that trading in the underlying LEAPS Options is limited or absent, the value of the Fund's LEAPS Options may decrease. There is no guarantee that a liquid secondary trading market will exist for the LEAPS Options. The trading in LEAPS Options may be less deep and liquid than the market for certain other securities. In a less liquid market for the LEAPS Options, terminating the LEAPS Options may require the payment of a premium or acceptance of a discounted price and may take longer to complete. In such a market, the liquidation of a large number of options may more significantly impact their price.

•  Market Maker Risk — If the Fund has lower average daily trading volumes, it may rely on a small number of third-party market makers to provide a market for the purchase and sale of Fund Shares. Any trading halt or other problem relating to the trading activity of these market makers could result in a dramatic change in the spread between the Fund's net asset value and the price at which the Fund Shares are trading on the Exchange, which could result in a decrease in value of the Fund Shares. In addition, decisions by market makers or authorized participants to reduce their role or step away from these activities in times of market stress could inhibit the effectiveness of the arbitrage process in maintaining the relationship between the underlying values of the Fund's portfolio securities and the Fund's market price. This reduced effectiveness could result in Fund Shares trading at a discount to net asset value and also in greater than normal intra-day bid-ask spreads for Fund Shares.

•  Market Risk — The risk that the securities markets will increase or decrease in value is considered market risk and applies to any security. If there is a general decline in the stock or fixed-income market, it is possible your investment may lose value regardless of the individual results of the companies in which the Fund invests.

•  Mortgage-related and Other Asset-backed Securities Risk — In addition to general fixed-income instrument risks, mortgage-related and asset-backed securities are subject to extension risk and prepayment risk.

•  Extension Risk — Rising interest rates tend to extend the duration of mortgage-related securities, making them more sensitive to changes in interest rates. As a result, in a period of rising interest rates, if the Fund holds mortgage-related securities, it may exhibit additional volatility.

•  Prepayment Risk — When interest rates decline, the value of mortgage-related securities with prepayment features may not increase as much as other fixed-income securities because borrowers may pay off their mortgages sooner than expected. In addition, the potential impact of prepayment on the price of asset-backed and mortgage-backed securities may be difficult to predict and result in greater volatility.

•  National Closed Market Trading Risk — To the extent that the underlying securities and/or other assets held by the Fund trade on non-U.S. exchanges or in non-U.S. markets that may be closed when the securities exchange on which Fund Shares trade is open, there are likely to be deviations between the current price of such an underlying security and the last quoted price for the underlying security (i.e., the Fund's quote from the closed non-U.S. market). The impact of a closed foreign market on the Fund is likely to be greater where a large portion of the Fund's underlying securities and/or other assets trade on that closed non-U.S. market or when the non-U.S. market is closed for unscheduled reasons. These deviations could result in premiums or discounts to the Fund's NAV that may be greater than those experienced by other ETFs.

•  New Fund Risk — The Fund is a recently organized investment company with a limited operating history. As a result, prospective investors have a limited track record or history on which to base their investment decision.

•  Non-Diversification Risk — The Fund is classified as "non-diversified" under the 1940 Act. As a result, the Fund is only limited as to the percentage of its assets which may be invested in the securities of any one issuer by the diversification requirements imposed by the Internal Revenue Code of 1986, as amended (the "Code").

•  Options Risk — The Fund's ability to close out its position as a purchaser or seller of an over-the-counter or exchange-listed put or call option is dependent, in part, upon the liquidity of the option market. There are significant differences between the securities and options markets that could result in an imperfect correlation among these markets, causing a given transaction not to achieve its objectives. The Fund's ability to utilize options successfully will depend on the ability of Calamos Advisors to predict pertinent market movements, which cannot be assured. The Fund will enter into option contracts pursuant to Rule 18f-4 under the 1940 Act, which requires the Fund to implement certain policies and

Calamos Alternative Nasdaq^®​ & Bond ETF

procedures designed to manage its derivatives risks, dependent upon the Fund's level of exposure to derivative instruments.

•  Other Investment Companies (including ETFs) Risk — The Fund may invest in the securities of other investment companies, including ETFs, to the extent that such investments are consistent with the Fund's investment objective and the policies are permissible under the 1940 Act. Investments in the securities of other investment companies, including ETFs, may involve duplication of advisory fees and certain other expenses. Additionally, if the investment company or ETF fails to achieve its investment objective, the value of the Fund's investment will decline, adversely affecting the Fund's performance. In addition, ETF shares potentially may trade at a discount or a premium and are subject to brokerage and other trading costs, which could result in greater expenses to the Fund. Whether the Fund will realize a gain or loss upon the sale of the such shares of ETFs depends upon whether the market value of the shares at the time of sale is above or below the price the Fund paid, taking into account transaction costs for the shares, and is not directly dependent upon the NAV of the shares of such funds. Because the market value of the shares will be determined by factors such as the relative demand for and supply of the shares in the market, general market conditions and other factors, it cannot be predicted whether such shares will trade at, below or above NAV, or below or above the public offering price for the shares. Common Shares, as well as shares issued by the ETFs, do not assure dividend payments. Dividends are paid only when declared by the boards of directors of the ETFs, and the level of dividends may vary over time. If an ETF reduces or eliminates the level of its regular dividends, this may reduce the level of dividends paid by the Fund, and may cause the market prices of the Fund's shares to fall.

In accordance with Section 12(d)(1)(F) of the 1940 Act, on which the Fund intends to rely to invest in other investment companies, the Fund will be restricted by provisions of the 1940 Act that limit the amount the Fund can invest in any one investment company to 3% of the investment company's total outstanding stock. As a result, the Fund may hold a smaller position in an investment company than if it were not subject to this restriction. However, if the Adviser determines that it is in the Fund's best interest to exceed the 3% limit, it may rely on Rule 12d1-4 under the 1940 Act. Rule 12d1-4 would permit the Fund to invest in excess of the 3% limit subject to certain conditions, including that the Fund must enter into a "Fund of Funds Investment Agreement" with the acquired investment company setting forth the material terms of the arrangement. In addition, to comply with provisions of the 1940 Act, on any matter upon which investment company stockholders are solicited to vote, the Adviser will vote investment company shares in the same general proportion as shares held by other stockholders of the investment company (a practice known as "echo voting"). This could limit the Fund's ability to support or oppose investment company shareholder voting matters.

•  Portfolio Selection Risk — The value of your investment may decrease if Calamos Advisors' judgment about the attractiveness, value or market trends affecting a particular security, issuer, industry or sector or about market movements is incorrect.

•  Portfolio Turnover Risk — The portfolio managers may actively and frequently trade securities or other instruments in the Fund's portfolio to carry out its investment strategies. A high portfolio turnover rate increases transaction costs, which may increase the Fund's expenses. Frequent and active trading may also cause adverse tax consequences for investors in the Fund due to an increase in short-term capital gains.

•  Premium-Discount Risk — Fund Shares may trade above or below their net asset value ("NAV"). The market prices of Fund Shares will generally fluctuate in accordance with changes in NAV as well as the relative supply of, and demand for, Fund Shares on the Exchange. The trading price of Fund Shares may deviate significantly from NAV during periods of market volatility.

•  Rule 144A Securities Risk — The Fund may invest in securities that are issued and sold through transactions under Rule 144A of the Securities Act of 1933. Under the supervision of its Board of Trustees, the Fund will determine whether Rule 144A Securities are illiquid. If qualified institutional buyers are unwilling to purchase these Rule 144A Securities, the percentage of the Fund's assets invested in illiquid securities would increase. Typically, the Fund purchases Rule 144A Securities if the Fund's adviser has determined them to be liquid. If any Rule 144A Security held by the Fund should become illiquid, the value of the security may be reduced and a sale of the security may be more difficult.

Calamos Alternative Nasdaq^®​ & Bond ETF

•  Secondary Market Trading Risk — Investors buying or selling Fund Shares in the secondary market will pay brokerage commissions or other charges imposed by brokers as determined by that broker. Brokerage commissions are often a fixed amount and may be a significant proportional cost for investors seeking to buy or sell relatively small amounts of Fund Shares. Although the Fund Shares are listed on the Exchange, there can be no assurance that an active or liquid trading market for them will develop or be maintained. In addition, trading in Fund Shares on the Exchange may be halted.

•  Sector Risk — To the extent the Fund invests a significant portion of its assets in a particular sector, a greater portion of the Fund's performance may be affected by the general business and economic conditions affecting that sector. Each sector may share economic risk with the broader market, however there may be economic risks specific to each sector. As a result, returns from those sectors may trail returns from the overall stock market, and it is possible that the Fund may underperform the broader market or experience greater volatility.

•  Senior Loan Risk — The risks associated with senior loans are similar to the risks of junk bonds, although senior loans are typically senior and secured, whereas junk bonds are often subordinated and unsecured. Investments in senior loans are typically below investment grade and are considered speculative because of the credit risk of their issuers. Such companies are more likely to default on their payments of interest and principal owed, and such defaults could reduce the Fund's NAV and income distributions. An economic downturn generally leads to a higher non-payment rate, and a senior loan may lose significant value before a default occurs. There is no assurance that the liquidation of the collateral would satisfy the claims of the borrower's obligations in the event of the non-payment of scheduled interest or principal, or that the collateral could be readily liquidated. Economic and other events (whether real or perceived) can reduce the demand for certain senior loans or senior loans generally, which may reduce market prices. Senior loans and other debt securities also are subject to the risk of price declines and to increases in prevailing interest rates, although floating-rate debt instruments such as senior loans are substantially less exposed to this risk than fixed-rate debt instruments. No active trading market may exist for certain senior loans, which may impair the ability of the Fund to realize full value in the event of the need to liquidate such assets. Adverse market conditions may impair the liquidity of some actively traded senior loans. Longer interest rate reset periods generally increase fluctuations in value as a result of changes in market interest rates.

•  Tax Risk — The Fund intends to elect and to qualify each year to be treated as a regulated investment company under Subchapter M of the Internal Revenue Code of 1986, as amended (the "Code"). The federal income tax treatment of securities in which the Fund may invest may not be clear or may be subject to recharacterization by the Internal Revenue Service. It could be more difficult to comply with the tax requirements applicable to regulated investment companies if the tax characterization of investments or the tax treatment of the income from such investments were successfully challenged by the Internal Revenue Service. Any such failure to comply with the rules applicable to regulated investment companies could cause the Fund to fail to qualify as such. If the Fund does not qualify as a regulated investment company for any taxable year, and certain relief provisions are not available, the Fund's taxable income will be subject to tax at the Fund level and to a further tax at the shareholder level when such income is distributed.

•  Trading Issues Risk — Trading in Fund Shares on the Exchange may be halted due to market conditions or for reasons that, in the view of the Exchange, make trading in shares inadvisable. In addition, trading in Fund Shares on the Exchange is subject to trading halts caused by extraordinary market volatility pursuant to the Exchange's "circuit breaker" rules. There can be no assurance that the requirements of the Exchange necessary to maintain the listing of the Fund will continue to be met or will remain unchanged. The Fund may have difficulty maintaining its listing on the Exchange in the event the Fund's assets are small, the Fund does not have enough shareholders, or if the Fund is unable to proceed with creation and/or redemption orders.

•  U.S. Government Security Risk — Some securities issued by U.S. Government agencies or government-sponsored enterprises are not backed by the full faith and credit of the U.S. and may only be supported by the right of the agency or enterprise to borrow from the U.S. Treasury. There can be no assurance that the U.S. Government will always provide financial support to those agencies or enterprises.

•  Valuation Risk — During periods of reduced market liquidity or in the absence of readily available market quotations for the holdings of the Fund, the ability of the Fund to value the FLEX Options and/or LEAPS Options may become more

Calamos Alternative Nasdaq^®​ & Bond ETF

difficult. In market environments where there is reduced availability of reliable objective pricing data, the judgment of Calamos Advisors in determining the fair value of the security may play a greater role. While such determinations may be made in good faith, it may nevertheless be more difficult for the Fund to accurately assign a daily value.

Fund Performance

Investment Adviser

Calamos Advisors LLC ("Calamos Advisors" or the "Adviser")

Portfolio Managers

Other Important Information Regarding Fund Shares

Portfolio Holdings. The Fund's portfolio holdings are disclosed on its website daily after the close of trading on the Exchange and prior to the opening of trading on the Exchange the following day. A description of the Fund's policies and procedures with respect to the disclosure of the Fund's portfolio holdings is available in the Fund's Statement of Additional Information ("SAI").

Premium/Discount Information. Information about the premiums and discounts at which the Fund's Shares have traded will be available at www.calamos.com.

Purchase and Sale of Fund Shares

The Fund will issue (or redeem) Fund Shares to certain institutional investors (typically market makers or other broker-dealers) only in large blocks of Fund Shares known as "Creation Units." Creation Unit transactions are conducted in exchange for the deposit or delivery of a designated portfolio of in-kind securities and/or cash.

Individual Fund Shares may only be purchased and sold on the Exchange, other national securities exchanges, electronic crossing networks and other alternative trading systems through your broker-dealer at market prices. Because Fund Shares trade at market prices rather than at net asset value ("NAV"), Fund Shares may trade at a price greater than NAV (premium) or less than NAV (discount). When buying or selling Fund Shares in the secondary market, you may incur costs attributable to the difference between the highest price a buyer is willing to pay to purchase Fund Shares (bid) and the lowest price a seller is willing to accept for Fund Shares (ask) (the "bid-ask spread"). Recent information regarding the Fund's NAV, market price, premiums and discounts, and bid-ask spreads is available at https://www.calamos.com/.

Tax Information

Net investment income and capital gains distributions you receive from the Fund generally are subject to federal income taxes and may also be subject to state and local taxes. The Fund intends to distribute net investment income, if any, monthly, and capital gains, if any, at least annually.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase shares of the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies may pay the intermediary for the sale of Fund Shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary's website for more information.

Additional Information About Investment Strategies and Related Risks

The Fund's investment objective, the 80% investment strategy and each of the policies described herein are non-fundamental policies that may be changed by the Board of Trustees of the Trust (the "Board") without shareholder approval. The Fund may liquidate and terminate at any time without shareholder approval.

What are the investment objective and principal strategies for the Fund?

The Fund's investment objective is attractive risk-adjusted total return through capital appreciation and current income.

The Fund is an actively managed ETF that seeks to deliver convertible security-like exposure to companies within the Nasdaq-100 Index^®​. This investment approach is an alternative way to access Nasdaq-100^®​ stocks by seeking to offer upside potential through the options and seeking to limit the downside through the fixed income portfolio. This is an alternative approach to outright equity investing. To achieve this exposure through investment in alternative instruments, the Fund will use a hybrid investment approach that utilizes equity and fixed income strategies. The Fund pursues its objective by investing, under normal circumstances, at least 80%, but up to 100%, of its net assets (plus borrowings for investment purposes, if any) in a portfolio of equity instruments (including options and equity ETFs) and fixed income instruments (including bonds and fixed income ETFs) intended to deliver convertible security-like exposure to companies in the Nasdaq-100 Index^®​. The Fund will consider the investments of underlying funds when determining compliance with its 80% policy. The Fund's investment adviser is Calamos Advisors.

The equity exposure will be achieved through investment in alternative instruments by purchasing the right to acquire an optimal number of stocks selected from the Nasdaq-100 Index^®​ based on a variety of factors including but not limited to liquidity and market capitalization and purchasing the right to acquire the corresponding stocks. In addition, equity exposure also may be achieved through investments in equity ETFs. The fixed income instruments will be selected based on credit quality, yield, duration, liquidity, and such other factors as deemed relevant by the Adviser. The fixed income instruments are intended to serve as a base for the Fund's portfolio by creating bond-like returns.

The Adviser has the flexibility to actively manage the equity exposure by both buying and selling options on equities, equity ETFs, warrants, long-dated call options ("LEAPS Options"), Flexible Exchange^®​ Options ("FLEX Options"), or similar instruments determining the option delta, strikes and maturity. Under normal circumstances, the Fund will generally not hold equity or cash in large amounts, choosing instead to re-deploy excess cash into its principal investment strategy.

The Adviser has the flexibility to actively manage the fixed income exposure through the selection of the underlying fixed income instruments that the Adviser believes will add value over owning U.S. Treasuries; determining the duration and credit quality; and the portfolio rebalancing method and frequency. The fixed-income instruments in which the Fund may invest include, among others, obligations of U.S., state, and local governments, their agencies and instrumentalities; mortgage- and asset-backed debt securities (including to-be announced mortgage-backed securities or TBAs); corporate debt securities, repurchase agreements, convertible securities, money market instruments, Treasury Bills, and other securities believed to have debt-like characteristics (such as preferred securities and corporate loans and related assignments and participations). The Fund's exposure to fixed income may be obtained in part through investments in ETFs and other investment companies.

The Fund may invest in investment grade debt securities (those rated BBB or higher by S&P, or Baa or higher by Moody's), which include securities issued or guaranteed by the U.S. government, its agencies and instrumentalities, as well as securities rated or subject to a guarantee that is rated within the investment grade categories listed by at least one of the Nationally Recognized Statistical Rating Organizations (NRSROs), and in below investment grade debt securities, which are sometimes referred to as high yield or "junk" bonds, which include bonds, bank loans and preferred securities. Junk bonds are securities rated BB or lower by S&P, or Ba or lower by Moody's or securities that are not rated but are considered Calamos Advisors to be of similar quality. These debt securities may include mortgage-backed, mortgage-related and other asset-backed securities, which directly or indirectly represent a participation in, or are secured by and payable from, mortgage loans, real property, or other assets such as car loans or aviation financing. The Fund's investments in debt securities will have no limits with regard to maturity, duration, credit quality, or geographic concentration.

Additional Information About Investment Strategies and Related Risks

The Fund's investments may be domiciled in any country and held in U.S. dollar and non-U.S. dollar denominations. With respect to the equity options component of its strategy, the Fund will not allocate more than 10% to a given name or issuer. Under normal circumstances, the Fund will seek to deliver convertible security-like exposure to companies in the Nasdaq-100 Index^®​.

The Fund is classified as "non-diversified" under the Investment Company Act of 1940, as amended (the "1940 Act").

Changes in 80% policy

The Fund has adopted a non-fundamental operating policy that requires it, under normal circumstances, to invest at least 80%, but up to 100%, of its net assets (plus borrowings for investment purposes, if any) in a portfolio of equity instruments (including options and equity ETFs) and fixed income instruments (including bonds and fixed income ETFs) intended to deliver convertible security-like exposure to companies in the Nasdaq-100 Index^®​. Although this requirement may be changed by the Board of Trustees without shareholder approval, the Fund will notify shareholders in writing at least 60 days prior to any change in its 80% policy.

Non-Principal Investments

Cash Equivalents and Short-Term Investments

The Fund may invest in securities with maturities of less than one year or cash equivalents, or it may hold cash. The percentage of the Fund invested in such holdings varies and depends on several factors, including market conditions. For temporary defensive purposes and during periods of high cash inflows or outflows, the Fund may invest part or all of its assets in these securities or it may hold cash. During such periods, the Fund may not be able to achieve its investment objective. The Fund may adopt a defensive strategy when the portfolio managers believe securities in which the Fund normally invests have elevated risks due to political or economic factors and in other extraordinary circumstances. For more information on eligible short-term investments, see the SAI.

Illiquid Investments

The Fund may invest up to 15% of its net assets in securities and other instruments that are, at the time of investment, illiquid (determined using the Securities and Exchange Commission's standard applicable to investment companies, i.e., any investment that the Fund reasonably expects cannot be sold or disposed of in current market conditions in seven calendar days or less without the sale or disposition significantly changing the market value of the investment). For this purpose, illiquid investments may include, but are not limited to, certain restricted securities (securities the disposition of which is restricted under the federal securities laws), certain securities that may only be resold pursuant to Rule 144A under the Securities Act, and certain repurchase agreements, among others.

Risks of Investing in the Fund

This prospectus describes the risks you may face as an investor in the Fund. It is important to keep in mind that generally, investments with a higher potential reward also have a higher risk of losing money. The reverse is also commonly true: the lower the risk, the lower the potential reward. However, as you consider an investment in the Fund, you should also take into account your tolerance for the daily fluctuations of the financial markets and whether you can afford to leave your money in this investment for a long period of time to ride out down periods.

As with any security, there are market and investment risks associated with your investment in the Fund. The value of your investment will fluctuate over time, and it is possible to lose money. The principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a "principal risk" of investing in the Fund, regardless of the order in which it appears.

In response to market, economic, political, or other conditions, the Fund may temporarily invest for defensive purposes that are inconsistent with the Fund's principal investment strategies. If the Fund does so, different factors could affect the Fund's performance, and the Fund may not achieve its investment objective.

Additional Information About Investment Strategies and Related Risks

Principal Risks

Authorized Participant Concentration Risk. Only an Authorized Participant may engage in creation or redemption transactions directly with the Fund, and none of those Authorized Participants is obligated to engage in creation and/or redemption transactions. The Fund has a limited number of institutions that may act as Authorized Participants on an agency basis (i.e., on behalf of other market participants). To the extent that Authorized Participants exit the business or are not able or willing to proceed with creation or redemption orders with respect to the Fund and no other Authorized Participant is able to step forward to create or redeem, Fund Shares may be more likely to trade at a premium or discount to NAV and possibly face trading halts or delisting. Authorized Participant concentration risk may be heightened for ETFs, such as the Fund, that invest in securities issued by non-U.S. issuers or other securities or instruments that have lower trading volumes.

Costs of Buying and Selling Fund Shares. Due to the costs of buying or selling Fund Shares, including brokerage commissions imposed by brokers and bid/ask spreads, frequent trading of Fund Shares may significantly reduce investment results and an investment in Fund Shares may not be advisable for investors who anticipate regularly making small investments.

Debt Securities Risk. Debt securities are subject to various risks, including interest rate risk, credit risk and default risk.

Interest Rate Risk. Interest rate risk is the risk that the Fund's investments in debt securities will decrease in value as a result of an increase in interest rates. Generally, there is an inverse relationship between the value of a debt security and interest rates. Therefore, the value of debt securities generally decrease in periods when interest rates are rising. In addition, interest rate changes typically have a greater effect on prices of longer-term debt securities than shorter-term debt securities. Changes in interest rates by the Federal Reserve Board, and other events affecting fixed-income markets, may subject a Fund to heightened interest rate risk as a result of a rise in interest rates. In addition, the Fund is subject to the risk that interest rates may exhibit increased volatility, which could cause the Fund's net asset value to fluctuate more. A decrease in fixed-income market maker capacity may act to decrease liquidity in the fixed-income markets and act to further increase volatility, affecting the Fund's return. Many financial instruments use or may use a floating rate which historically had been based on the London Interbank Offered Rate ("LIBOR"), which was the offered rate for short-term Eurodollar deposits between major international banks. In connection with the global transition away from LIBOR led by regulators and market participants, LIBOR was last published on a representative basis at the end of June 2023. Actions by regulators have resulted in the establishment of alternative reference rates to LIBOR, such as the Secured Overnight Financing Rate (SOFR), and the transition to new reference rates continues. The transition away from LIBOR and the use of replacement rates has gone relatively smoothly, but the full impact of the transition away from LIBOR on the Fund or the financial instruments in which the Fund invests cannot yet be fully determined.

Credit Risk. Credit risk is the risk that a debt security could deteriorate in quality to such an extent that its rating is downgraded or its market value declines relative to comparable securities. Changes in actual or perceived creditworthiness may occur quickly. If the Fund holds securities that have been downgraded, or that default on payment, such Fund's performance could be negatively affected.

Default Risk. Default risk refers to the risk that a company that issues a debt security will be unable to fulfill its obligation to repay principal and interest. The lower a bond is rated, the greater its default risk. To the extent the Fund holds securities that have been downgraded, or that default on payment, its performance could be negatively affected.

Emerging Markets Risk. Emerging market countries may have relatively unstable governments and economies based on only a few industries, which may cause greater instability. The value of emerging market securities will likely be particularly sensitive to changes in the economies of such countries. These countries are also more likely to experience higher levels of inflation, deflation or currency devaluations, which could hurt their economies and securities markets. Certain emerging markets are sometimes referred to as "frontier markets."

Frontier markets, the least advanced capital markets in the developing world, are among the riskiest markets in the world in which to invest. Investments in this sector are typically illiquid, nontransparent and subject to very low regulation levels as well as high transaction fees, and may also have substantial political and currency risk.

Additional Information About Investment Strategies and Related Risks

Equity Securities Risk. Equity investments are subject to greater fluctuations in market value than other asset classes as a result of such factors as a company's business performance, investor perceptions, stock market trends and general economic conditions.

ETF Risk. The Fund may invest in ETFs. Many ETFs use a "passive" investment strategy and seek to replicate the performance of a market index. Such ETFs do not take defensive positions in volatile or declining markets their shares may trade below net asset value. While some ETFs seek to achieve the same return as a particular market index, the performance of the ETF may diverge from the performance of the index. Some ETFs are actively managed ETFs and do not track a particular index which indirectly subjects an investor to active management risk. An active secondary market in ETF shares may not develop or be maintained and may be halted or interrupted due to actions by its listing exchange, unusual market conditions or other reasons. There can be no assurance that an ETF's shares will continue to be listed on an active exchange. In addition, shareholders bear both their proportionate share of the Fund's expenses and, indirectly, the ETF's expenses, incurred through the Fund's ownership of the ETF. Because the expenses and costs of an ETF are shared by its investors, redemptions by other investors in the ETF could result in decreased economies of scale and increased operating expenses for such ETF. These transactions might also result in higher brokerage, tax or other costs for the ETF. This risk may be particularly important when one investor owns a substantial portion of the ETF. There is a risk that ETFs in which the Fund invests may terminate due to extraordinary events. For example, any of the service providers to ETFs, such as the trustee or sponsor, may close or otherwise fail to perform their obligations to the ETF, and the ETF may not be able to find a substitute service provider. Also, certain ETFs may be dependent upon licenses to use various indexes as a basis for determining their compositions and/or otherwise to use certain trade names. If these licenses are terminated, the ETFs may also terminate. In addition, an ETF may terminate if its net assets fall below a certain amount.

FLEX Options Risk. The Fund may invest in FLEX Options issued and guaranteed for settlement by The Options Clearing Corporation ("OCC"). FLEX Options are customized option contracts that trade on an exchange but provide investors with the ability to customize key contract terms like strike price, style and expiration date while achieving price discovery in competitive, transparent auctions markets and avoiding the counterparty exposure of over-the-counter options positions. Like traditional exchange-traded options, FLEX Options are guaranteed for settlement by the OCC, a market clearinghouse that guarantees performance by counterparties to certain derivatives contracts. The Fund bears the risk that the OCC will be unable or unwilling to perform its obligations under the FLEX Options contracts. Additionally, FLEX Options may be illiquid, and in such cases, the Fund may have difficulty closing out certain FLEX Options positions at desired times and prices. The FLEX Options held by the Fund will be exercisable at the strike price only on their expiration date. Prior to the expiration date, the value of the FLEX Options will be determined based upon market quotations or using other recognized pricing methods. The value of the FLEX Options prior to the expiration date may vary because of related factors other than the value of the reference asset. Factors that may influence the value of the FLEX Options, other than gains or losses in the reference asset, may include interest rate changes, changing supply and demand, decreased liquidity of the FLEX Options and changing volatility levels of the reference asset. In connection with the creation and redemption of Fund Shares, to the extent market participants are not willing or able to enter into FLEX Option transactions with the Fund at prices that reflect the market price of the Fund Shares, the Fund's net asset value ("NAV") and, in tum the share price of the Fund, could be negatively impacted. The Fund may experience substantial downside from specific FLEX Option positions and certain FLEX Option positions may expire worthless.

Foreign Securities Risk. Risks associated with investing in foreign securities include fluctuations in the exchange rates of foreign currencies that may affect the U.S. dollar value of a security, the possibility of substantial price volatility as a result of political and economic instability in the foreign country, less public information about issuers of securities, different securities regulation, different accounting, auditing and financial reporting standards and less liquidity than in U.S. markets.

High Yield Fixed-Income Securities (Junk Bonds) Risk. Investment in junk bonds entails a greater risk than an investment in higher-rated securities. Although junk bonds typically pay higher interest rates than investment-grade bonds, there is a greater likelihood that the company issuing the junk bond will default on interest and principal payments. In the event of an issuer's bankruptcy, claims of other creditors may have priority over the claims of junk bond holders, leaving few or no assets to repay them. Junk bonds are also more sensitive to adverse economic changes or individual corporate developments than higher quality bonds. During a period of adverse economic changes, including a period of rising interest rates, companies issuing junk bonds may be unable to make principal and interest payments.

Additional Information About Investment Strategies and Related Risks

Large-Capitalization Investing Risk. Large-capitalization stocks as a group could fall out of favor with the market, which may cause a Fund to underperform funds that focus on other types of stocks. In addition, larger, more established companies may be unable to respond quickly to new competitive challenges such as changes in technology and consumer preferences. Many larger companies also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

LEAPS Options Risk. The Fund's investments in options contracts may include long-term equity anticipation securities known as LEAPS Options. LEAPS Options are long-term exchange-traded call options that allow holders the opportunity to participate in the underlying securities' appreciation in excess of a specified strike price without receiving payments equivalent to any cash dividends declared on the underlying securities. A holder of a LEAPS Option will be entitled to receive a specified number of shares of the underlying stock upon payment of the exercise price, and therefore the LEAPS Option will be exercisable at any time the price of the underlying stock is above the strike price. However, if at expiration the price of the underlying stock is at or below the strike price, the LEAPS Option will expire and be worthless. The Fund purchases call option contracts. By purchasing call option contracts, the Fund purchases the right (but not the obligation) to purchase the reference asset at a pre-determined price (the "strike price") in exchange for a premium to the seller.

Liquidity Risk — FLEX Options. In the event that trading in the underlying FLEX Options is limited or absent, the value of the Fund's FLEX Options may decrease. There is no guarantee that a liquid secondary trading market will exist for the FLEX Options. The trading in FLEX Options may be less deep and liquid than the market for certain other securities, including certain non-customized option contracts. In a less liquid market for the FLEX Options, terminating the FLEX Options may require the payment of a premium or acceptance of a discounted price and may take longer to complete. Additionally, the liquidation of a large number of FLEX Options may more significantly impact the price in a less liquid market. Further, the Fund requires a sufficient number of participants to facilitate the purchase and sale of options on an exchange to provide liquidity to the Fund for its FLEX Option positions. A less liquid trading market may adversely impact the value of the FLEX Options and the value of your investment.

Liquidity Risk — LEAPS Options. In the event that trading in the underlying LEAPS Options is limited or absent, the value of the Fund's LEAPS Options may decrease. There is no guarantee that a liquid secondary trading market will exist for the LEAPS Options. The trading in LEAPS Options may be less deep and liquid than the market for certain other securities. In a less liquid market for the LEAPS Options, terminating the LEAPS Options may require the payment of a premium or acceptance of a discounted price and may take longer to complete. In such a market, the liquidation of a large number of options may more significantly impact their price.

Market Maker Risk. If the Fund has lower average daily trading volumes, it may rely on a small number of third-party market makers to provide a market for the purchase and sale of Fund Shares. Any trading halt or other problem relating to the trading activity of these market makers could result in a dramatic change in the spread between the Fund's net asset value and the price at which the Fund Shares are trading on the Exchange, which could result in a decrease in value of the Fund Shares. In addition, decisions by market makers or authorized participants to reduce their role or step away from these activities in times of market stress could inhibit the effectiveness of the arbitrage process in maintaining the relationship between the underlying values of the Fund's portfolio securities and the Fund's market price. This reduced effectiveness could result in Fund Shares trading at a discount to net asset value and also in greater than normal intra-day bid-ask spreads for Fund Shares.

Market Risk. The risk that the securities markets will increase or decrease in value is considered market risk and applies to any security. If there is a general decline in the stock or fixed-income market, it is possible your investment may lose value regardless of the individual results of the companies in which the Fund invests.

Mortgage-related and Other Asset-backed Securities Risk. In addition to general fixed-income instrument risks, mortgage-related and asset-backed securities are subject to extension risk and prepayment risk.

Extension Risk. Rising interest rates tend to extend the duration of mortgage-related securities, making them more sensitive to changes in interest rates. As a result, in a period of rising interest rates, if the Fund holds mortgage-related securities, it may exhibit additional volatility.

Additional Information About Investment Strategies and Related Risks

Prepayment Risk. When interest rates decline, the value of mortgage-related securities with prepayment features may not increase as much as other fixed-income securities because borrowers may pay off their mortgages sooner than expected. In addition, the potential impact of prepayment on the price of asset-backed and mortgage-backed securities may be difficult to predict and result in greater volatility.

National Closed Market Trading Risk. To the extent that the underlying securities and/or other assets held by the Fund trade on non-U.S. exchanges or in non-U.S. markets that may be closed when the securities exchange on which Fund Shares trade is open, there are likely to be deviations between the current price of such an underlying security and the last quoted price for the underlying security (i.e., the Fund's quote from the closed non-U.S. market). The impact of a closed foreign market on the Fund is likely to be greater where a large portion of the Fund's underlying securities and/or other assets trade on that closed non-U.S. market or when the non-U.S. market is closed for unscheduled reasons. These deviations could result in premiums or discounts to the Fund's NAV that may be greater than those experienced by other ETFs.

New Fund Risk. The Fund is a recently organized investment company with a limited operating history. As a result, prospective investors have a limited track record or history on which to base their investment decision.

Non-Diversification Risk. The Fund is classified as "non-diversified" under the 1940 Act. As a result, the Fund is only limited as to the percentage of its assets which may be invested in the securities of any one issuer by the diversification requirements imposed by the Code. The Fund may invest a relatively high percentage of its assets in a limited number of issuers. As a result, the Fund may be more susceptible to a single adverse economic or regulatory occurrence affecting one or more of these issuers, experience increased volatility and be highly invested in certain issuers.

Options Risk. There are significant differences between the securities and options markets that could result in an imperfect correlation among these markets, causing a given transaction not to achieve its objectives. The Fund's ability to utilize options successfully will depend on Calamos Advisors' ability to predict pertinent market movements, which cannot be assured.

The Fund's ability to close out its position as a purchaser or seller of an Options Clearing Corporation or exchange-listed put or call option is dependent, in part, upon the liquidity of the options market. If the Fund were unable to close out an option that it had purchased on a security, it would have to exercise the option to realize any profit or the option would expire and become worthless. If the Fund were unable to close out a covered call option that it had written on a security, it would not be able to sell the underlying security until the option expired. As the writer of a covered call option on a security, the Fund foregoes, during the option's life, the opportunity to profit from increases in the market value of the security covering the call option above the sum of the premium and the exercise price of the call. The hours of trading for listed options may not coincide with the hours during which the underlying financial instruments are traded. To the extent that the option markets close before the markets for the underlying financial instruments, significant price and rate movements can take place in the underlying markets that cannot be reflected in the option markets until the next trading day.

Unless the parties provide for it, there is no central clearing or guaranty function in an over-the-counter option. As a result, if the counterparty fails to make or take delivery of the security or other instrument underlying an over-the-counter option it has entered into with the Fund or fails to make a cash settlement payment due in accordance with the terms of that option, the Fund will lose any premium it paid for the option as well as any anticipated benefit of the transaction. Accordingly, Calamos Advisors must assess the creditworthiness of each such counterparty or any guarantor or credit enhancement of the counterparty's credit to determine the likelihood that the terms of the over-the-counter option will be satisfied.

The Fund may also purchase or write over-the-counter put or call options, which involves risks different from, and possibly greater than, the risks associated with exchange-listed put or call options. In some instances, over-the-counter put or call options may expose the Fund to the risk that a counterparty may be unable or unwilling to perform according to a contract, and that any deterioration in a counterparty's creditworthiness could adversely affect the instrument. In addition, the Fund may be exposed to a risk that losses may exceed the amount originally invested. The Fund will enter into option contracts pursuant to Rule 18f-4 under the 1940 Act, which requires the Fund to implement certain policies and procedures designed to manage its derivatives risks, dependent upon the Fund's level of exposure to derivative instruments.

Additional Information About Investment Strategies and Related Risks

Other Investment Companies (including ETFs) Risk. The Fund may invest in the securities of other investment companies, including ETFs, to the extent that such investments are consistent with the Fund's investment objective and the policies are permissible under the 1940 Act. Investments in the securities of other investment companies, including ETFs, may involve duplication of advisory fees and certain other expenses. Additionally, if the investment company or ETF fails to achieve its investment objective, the value of the Fund's investment will decline, adversely affecting the Fund's performance. In addition, ETF shares potentially may trade at a discount or a premium and are subject to brokerage and other trading costs, which could result in greater expenses to the Fund. Whether the Fund will realize a gain or loss upon the sale of the such shares of ETFs depends upon whether the market value of the shares at the time of sale is above or below the price the Fund paid, taking into account transaction costs for the shares, and is not directly dependent upon the NAV of the shares of such funds. Because the market value of the shares will be determined by factors such as the relative demand for and supply of the shares in the market, general market conditions and other factors, it cannot be predicted whether such shares will trade at, below or above NAV, or below or above the public offering price for the shares. Common Shares, as well as shares issued by the ETFs, do not assure dividend payments. Dividends are paid only when declared by the boards of directors of the ETFs, and the level of dividends may vary over time. If an ETF reduces or eliminates the level of its regular dividends, this may reduce the level of dividends paid by the Fund, and may cause the market prices of the Fund's shares to fall.

In accordance with Section 12(d)(1)(F) of the 1940 Act, on which the Fund intends to rely to invest in other investment companies, the Fund will be restricted by provisions of the 1940 Act that limit the amount the Fund can invest in any one investment company to 3% of the investment company's total outstanding stock. As a result, the Fund may hold a smaller position in an investment company than if it were not subject to this restriction. However, if the Adviser determines that it is in the Fund's best interest to exceed the 3% limit, it may rely on Rule 12d1-4 under the 1940 Act. Rule 12d1-4 would permit the Fund to invest in excess of the 3% limit subject to certain conditions, including that the Fund must enter into a "Fund of Funds Investment Agreement" with the acquired investment company setting forth the material terms of the arrangement. In addition, to comply with provisions of the 1940 Act, on any matter upon which investment company stockholders are solicited to vote, the Adviser will vote investment company shares in the same general proportion as shares held by other stockholders of the investment company (a practice known as "echo voting"). This could limit the Fund's ability to support or oppose investment company shareholder voting matters.

Portfolio Selection Risk. The value of your investment may decrease if the judgment of Calamos Advisors about the attractiveness, value or market trends affecting a particular security, issuer, industry, or sector or about market movements is incorrect.

Portfolio Turnover Risk. Engaging in active and frequent trading of securities may result in a higher than average level of capital gains and greater transaction costs to the Fund, including brokerage commissions or dealer mark-ups and other transaction costs on the sale and reinvestments of securities. Such sales may also result in the realization of capital gains, including short-term capital gains (which are taxed at ordinary income tax rates for federal income tax purposes, rather than at lower capital gains rates) and may adversely impact the Fund's performance. It is possible that the Fund engaging in active and frequent trading may be required to make significant distributions derived from taxable gains, regardless of the Fund's net longer term performance. The trading costs and tax effects associated with portfolio turnover will adversely affect the Fund's performance and lower the Fund's effective return for investors.

Premium-Discount Risk. The Fund Shares may trade above or below their net asset value ("NAV"). The market prices of Fund Shares will generally fluctuate in accordance with changes in NAV as well as the relative supply of, and demand for, Fund Shares on the Exchange. The trading price of Fund Shares may deviate significantly from NAV during periods of market volatility.

Rule 144A Securities Risk. The Fund may invest in securities that are issued and sold through transactions under Rule 144A of the Securities Act of 1933. Under the supervision of its Board of Trustees, the Fund will determine whether Rule 144A Securities are illiquid. If qualified institutional buyers are unwilling to purchase these Rule 144A Securities, the percentage of the Fund's assets invested in illiquid securities would increase. Typically, the Fund purchases Rule 144A Securities if the Fund's adviser has determined them to be liquid. If any Rule 144A Security held by the Fund should become illiquid, the value of the security may be reduced and a sale of the security may be more difficult.

Additional Information About Investment Strategies and Related Risks

Secondary Market Trading Risk. Investors buying or selling Fund Shares in the secondary market will pay brokerage commissions or other charges imposed by brokers as determined by that broker. Brokerage commissions are often a fixed amount and may be a significant proportional cost for investors seeking to buy or sell relatively small amounts of Fund Shares. Although the Fund Shares are listed on the Exchange, there can be no assurance that an active or liquid trading market for them will develop or be maintained. In addition, trading in Fund Shares on the Exchange may be halted.

Sector Risk. To the extent the Fund invests a significant portion of its assets in a particular sector, a greater portion of the Fund's performance may be affected by the general business and economic conditions affecting that sector. Each sector may share economic risk with the broader market, however there may be economic risks specific to each sector. As a result, returns from those sectors may trail returns from the overall stock market and it is possible that the Fund may underperform the broader market, or experience greater volatility.

Senior Loan Risk. The risks associated with senior loans are similar to the risks of junk bonds, although senior loans typically are senior and secured, whereas junk bonds often are subordinated and unsecured. Investments in senior loans typically are below investment grade and are considered speculative because of the credit risk of their issuers. Such companies are more likely to default on their payments of interest and principal owed, and such defaults could reduce the Fund's NAV and income distributions. An economic downturn generally leads to a higher non-payment rate, and a senior loan may lose significant value before a default occurs. There is no assurance that the liquidation of the collateral would satisfy the claims of the borrower's obligations in the event of the non-payment of scheduled interest or principal, or that the collateral could be readily liquidated. Economic and other events (whether real or perceived) can reduce the demand for certain senior loans or senior loans generally, which may reduce market prices. Senior loans and other debt securities also are subject to the risk of price declines and to increases in prevailing interest rates, although floating-rate debt instruments such as senior loans in which the Fund may be expected to invest are substantially less exposed to this risk than fixed-rate debt instruments. No active trading market may exist for certain senior loans, which may impair the ability of the Fund to realize full value in the event of the need to liquidate such assets. Adverse market conditions may impair the liquidity of some actively traded senior loans. Longer interest rate reset periods generally increase fluctuations in value as a result of changes in market interest rates.

Some loans are subject to the risk that a court, pursuant to fraudulent conveyance or other similar laws, could subordinate the loans to presently existing or future indebtedness of the borrower or take other action detrimental to lenders, including the Fund, such as invalidation of loans or causing interest previously paid to be refunded to the borrower. Investments in loans also are subject to the risk of changes in legislation or state or federal regulations. If such legislation or regulations impose additional requirements or restrictions on the ability of financial institutions to make loans, the availability of loans for investment by the Fund may be adversely affected. Many loans are not registered with the SEC or any state securities commission and often are not rated by any nationally recognized rating service. Generally, there is less readily available, reliable information about most loans than is the case for many other types of securities. Although a loan may be senior to equity and other debt securities in a borrower's capital structure, such obligations may be structurally subordinated to obligations of the borrower's subsidiaries.

There is no organized exchange on which loans are traded and reliable market quotations may not be readily available. Therefore, elements of judgment may play a greater role in valuation of loans than for securities with a more developed secondary market and the Fund may not realize full value in the event of the need to sell a loan. To the extent that a secondary market does exist for certain loans, the market may be subject to volatility, irregular trading activity, wide bid/ask spreads, decreased liquidity and extended trade settlement periods, any of which may impair the Fund's ability to sell loans within its desired time frame or at an acceptable price and its ability to accurately value existing and prospective investments. Extended trade settlement periods for certain loans may result in cash not being immediately available to the Fund upon sale of the loan. As a result, the Fund may have to sell other investments with shorter settlement periods or engage in borrowing transactions to raise cash to meet its obligations.

Tax Risk. The Fund intends to elect and to qualify each year to be treated as a regulated investment company under Subchapter M of the Code. The federal income tax treatment of securities in which the Fund may invest may not be clear or may be subject to recharacterization by the Internal Revenue Service. It could be more difficult to comply with the tax requirements applicable to regulated investment companies if the tax characterization of investments or the tax treatment of

Additional Information About Investment Strategies and Related Risks

the income from such investments were successfully challenged by the Internal Revenue Service. Any such failure to comply with the rules applicable to regulated investment companies could cause the Fund to fail to qualify as such. If the Fund does not qualify as a regulated investment company for any taxable year, and certain relief provisions are not available, the Fund's taxable income will be subject to tax at the Fund level and to a further tax at the shareholder level when such income is distributed.

Trading Issues Risk. Trading in Fund Shares on the Exchange may be halted due to market conditions or for reasons that, in the view of the Exchange, make trading in shares inadvisable. In addition, trading in Fund Shares on the Exchange is subject to trading halts caused by extraordinary market volatility pursuant to the Exchange's "circuit breaker" rules. There can be no assurance that the requirements of the Exchange necessary to maintain the listing of the Fund will continue to be met or will remain unchanged. The Fund may have difficulty maintaining its listing on the Exchange in the event the Fund's assets are small, the Fund does not have enough shareholders, or if the Fund is unable to proceed with creation and/or redemption orders.

U.S. Government Security Risk. Some securities issued by U.S. Government agencies or government-sponsored enterprises are not backed by the full faith and credit of the U.S. and may only be supported by the right of the agency or enterprise to borrow from the U.S. Treasury. There can be no assurance that the U.S. Government will always provide financial support to those agencies or enterprises.

Valuation Risk. During periods of reduced market liquidity or in the absence of readily available market quotations for the holdings of the Fund, the ability of the Fund to value the FLEX Options and/or LEAPS Options may become more difficult. In market environments where there is reduced availability of reliable objective pricing data, the judgment of Calamos Advisors in determining the fair value of the security may play a greater role. While such determinations may be made in good faith, it may nevertheless be more difficult for the Fund to accurately assign a daily value.

The following are non-principal risks that generally apply to the Fund:

Cybersecurity Risk. Investment companies, such as the Fund, and their service providers are exposed to operational and information security risks resulting from cyberattacks, which may result in financial losses to the Fund and its shareholders. Cyber- attacks include, among other behaviors, stealing or corrupting data maintained online or digitally, denial of service attacks on websites, "ransomware" that renders systems inoperable until ransom is paid, the unauthorized release of confidential information, or various other forms of cybersecurity breaches. Cyber-attacks affecting the Fund, Calamos Advisors, custodian, transfer agent, distributor, administrator, intermediaries, trading counterparties, and other third-party service providers may adversely impact the Fund or the companies in which the Fund invests, causing the Fund's investments to lose value or to prevent a shareholder redemption or purchase from clearing in a timely manner.

Inflation Risk. The risk that the value of assets or income from the Fund's investments will be worth less in the future as inflation decreases the value of payments at future dates is considered inflation risk. As inflation increases, the value of the Fund's portfolio could decline. Inflation rates may change frequently and drastically as a result of various factors and the Fund's investments may not keep pace with inflation, which may result in losses to the Fund's investors or adversely affect the value of shareholders' investments in the Fund.

Investment Management Risk. Whether the Fund achieves its investment objective(s) is significantly impacted by whether Calamos Advisors is able to choose suitable investments for the Fund.

Market Disruption Risk. Certain events have a disruptive effect on securities markets, including but not limited to, terrorist attacks, war and other geopolitical events or catastrophes. Calamos Advisors cannot predict the effect of similar events in the future on the U.S. or foreign economies. Certain securities such as high yield and equity securities tend to be impacted more by these events than other types of securities in terms of price and volatility.

Operational Risk. The Fund is subject to risks arising from various operational factors, including, but not limited to, human error, processing and communication errors, errors of the Fund's service providers, counterparties or other third-parties, failed or inadequate processes and technology or systems failures. The Fund relies on third-parties for a range of services, including custody. Any delay or failure relating to engaging or maintaining such service providers may affect the Fund's ability to meet its

Additional Information About Investment Strategies and Related Risks

investment objective. Although the Fund and the Adviser seek to reduce these operational risks through controls and procedures, there is no way to completely protect against such risks.

Recent Market Events. Since the 2008 financial crisis, financial markets throughout the world have experienced periods of increased volatility, depressed valuations, decreased liquidity and heightened uncertainty and turmoil. This turmoil resulted in unusual and extreme volatility in the equity and debt markets, in the prices of individual securities and in the world economy. Events that have contributed to these market conditions include, but are not limited to, major cybersecurity events, geopolitical events (such as wars (including Russia's military invasion of the Ukraine), terror attacks, natural or environmental disasters, country instability, and public health emergencies), measures to address budget deficits, downgrading of sovereign debt, dramatic changes in currency exchange rates, and public sentiment.

In addition, policy and legislative changes in the United States and in other countries are changing many aspects of financial regulation. The impact of these changes on the markets, and the practical implications for market participants, may not be fully known for some time. Widespread disease and virus epidemics and pandemics, such as the coronavirus outbreak, could likewise be highly disruptive, adversely affecting individual companies, sectors, industries, markets, currencies, interest and inflation rates, credit ratings, investor sentiment, and other factors affecting the value of the Fund's investments.

Portfolio security holdings disclosure

A description of the Fund's policies and procedures in connection with the disclosure of portfolio security holdings of the Fund is available in the Fund's SAI at www.calamos.com.

Fund Facts

Who manages the Fund?

Investment Adviser

The Fund is advised by Calamos Advisors LLC ("Calamos Advisors" or the "Adviser"), 2020 Calamos Court, Naperville, Illinois 60563. Calamos Advisors, an investment adviser registered with the SEC effective May 29, 1987, is a wholly owned subsidiary of Calamos Investments LLC ("CILLC"). CILLC's assets under management as of December 31, 2023, were $35 billion ($34 billion of which represented Calamos Advisors' assets under management). Calamos Asset Management, Inc. ("CAM") is the sole manager of CILLC. As of December 31, 2023, approximately 22% of the outstanding interests of CILLC was owned by CAM and the remaining approximately 78% of CILLC was owned by Calamos Partners LLC ("CPL") and John P. Calamos, Sr. CAM was owned by John P. Calamos, Sr. and John S. Koudounis, and CPL was owned by John S. Koudounis and Calamos Family Partners, Inc. ("CFP"). CFP was beneficially owned by members of the Calamos family, including John P. Calamos, Sr.

Subject to the overall authority of the Board of Trustees, Calamos Advisors provides continuous investment supervision and management to the Fund under a management agreement and also furnishes office space, equipment and management personnel. For these services, the Fund pays Calamos Advisors a fee based on its average daily net assets, which is accrued daily and paid on a monthly basis. The Fund will pay fees (before any reimbursement) under the management agreement in the following amounts as a percentage of its average net assets:

Out of this management fee, Calamos Advisors pays substantially all expenses of the Fund, including the cost of transfer agency, custody, fund administration, legal, audit and other service and license fees, except for distribution and service fees payable pursuant to a Rule 12b-1 plan, if any, acquired fund fees and expenses, brokerage commissions and other expenses connected with the execution of portfolio transactions, taxes, interest, and extraordinary expenses.

At a meeting held on September 1, 2023, the Board of Trustees approved the Investment Management Agreement for the Fund. A discussion regarding the basis for the Board's approval of the Investment Management Agreement on behalf of the Fund is included in the Fund's Form N-CSR for the fiscal year ended July 31, 2024.

Portfolio Managers

R. Matthew Freund. R. Matthew Freund joined Calamos Advisors in November 2016 as a Co-CIO, Head of Fixed Income Strategies, as well as a Senior Co-Portfolio Manager. Previously, he was SVP of Investment Portfolio Management and Chief Investment Officer at USAA Investments since 2010.

Shaheen Iqubal. Shaheen Iqubal joined Calamos Advisors in 2017 as Senior Vice President, Head of Quantitative Investments, Co-Head of Risk, and since January 2024 has been an Associate Portfolio Manager. Shaheen is responsible for oversight of our quantitative investment and risk management teams. Prior to joining the firm, Shaheen was Executive Director and Senior Quantitative Analyst in the applied research group at UBS Asset Management.

The Fund's SAI provides additional information about each portfolio manager, including other accounts they manage, their ownership in the Calamos Family of Funds and their compensation.

Management Approach

Calamos Advisors employs a "team of teams" approach to portfolio management, led by the Global CIO and our CIO team consisting of 5 Co-CIOs with specialized areas of investment expertise. The Global CIO and Co-CIO team are responsible for oversight of investment team resources, investment processes, performance and risk. As heads of investment verticals, Co-CIOs manage investment team members and, along with Co- Portfolio Managers and Associate Portfolio Managers, have day-to-day portfolio oversight and construction responsibilities of their respective investment strategies. While investment research professionals within each Co-CIO's team are assigned specific strategy responsibilities, they also provide support to other investment team verticals, creating deeper insights across a wider range of investment strategies. The combination of specialized investment teams with cross team collaboration results in what we call our team of teams approach.

Fund Facts

This team of teams approach is further reflected in the composition of Calamos Advisors' Investment Committee, made up of the Global CIO, the Co-CIO team, and the Global Head of Trading. Other members of the investment team participate in Investment Committee meetings in connection with specific investment related issues or topics as deemed appropriate.

The structure and composition of the Investment Committee results in a number of benefits, as it:

•  Leads to broader perspective on investment decisions: multiple viewpoints and areas of expertise feed into consensus;

•  Promotes collaboration between teams; and

•  Functions as a think tank with the goal of identifying ways to outperform the market on a risk-adjusted basis.

The objectives of the Investment Committee are to:

•  Form the firm's top-down macro view, market direction, asset allocation, and sector/country positioning.

•  Establish firm-wide secular and cyclical themes for review.

•  Review firm-wide and portfolio risk metrics, recommending changes where appropriate.

•  Review firm-wide, portfolio and individual security liquidity constraints.

•  Evaluate firm-wide and portfolio investment performance.

•  Evaluate firm-wide and portfolio hedging policies and execution.

•  Evaluate enhancements to the overall investment process.

R. Matthew Freund is a Senior Co-Portfolio Manager of the Fund. Shaheen Iqubal is an Associate Portfolio Manager of the Fund. Senior Co-Portfolio Managers and Associate Portfolio Managers are collectively referred to within this registration statement as "Portfolio Managers".

How to Buy and Sell Shares

Fund Shares are listed for secondary trading on the Exchange under the symbol CANQ and individual Fund Shares may only be purchased and sold in the secondary market through a broker-dealer. The Exchange and secondary markets are closed on weekends and also are generally closed on the following holidays: New Year's Day, Dr. Martin Luther King, Jr. Day, Presidents' Day, Good Friday, Memorial Day (observed), Juneteenth, Independence Day, Labor Day, Thanksgiving Day and Christmas Day. The Exchange may close early on the business day before certain holidays and on the day after Thanksgiving Day. Exchange holiday schedules are subject to change without notice. If you buy or sell Fund Shares in the secondary market, you will pay the secondary market price for Fund Shares. In addition, you may incur customary brokerage commissions and charges and may pay some or all of the spread between the bid and the offered price in the secondary market on each leg of a round trip (purchase and sale) transaction.

The trading prices of Fund Shares will fluctuate continuously throughout trading hours based on market supply and demand rather than the relevant Fund's net asset value, which is calculated at the end of each business day. Fund Shares will trade on the Exchange at prices that may be above (i.e., at a premium) or below (i.e., at a discount), to varying degrees, the daily net asset value of Fund Shares. The trading prices of Fund Shares may deviate significantly from the Fund's net asset value during periods of market volatility. Given, however, that Fund Shares can be issued and redeemed daily in Creation Units, the Adviser believes that large discounts and premiums to net asset value should not be sustained over long periods.

Authorized Participants may acquire shares directly from the Fund, and Authorized Participants may tender their shares for redemption directly to the Fund, at NAV per share only in Creation Units. Purchases and redemptions directly with the Fund must follow the Fund's procedures, which are described in the SAI.

The Fund may liquidate and terminate at any time without shareholder approval.

Book Entry

Fund Shares are held in book-entry form, which means that no stock certificates are issued. The Depository Trust Company ("DTC") or its nominee is the record owner of all outstanding Shares of the Fund and is recognized as the owner of all Shares for all purposes.

Fund Facts

Investors owning Fund Shares are beneficial owners as shown on the records of DTC or its participants. DTC serves as the securities depository for all Fund Shares. Participants in DTC include securities brokers and dealers, banks, trust companies, clearing corporations and other institutions that directly or indirectly maintain a custodial relationship with DTC. As a beneficial owner of Fund Shares, you are not entitled to receive physical delivery of stock certificates or to have Fund Shares registered in your name, and you are not considered a registered owner of Fund Shares. Therefore, to exercise any right as an owner of Fund Shares, you must rely upon the procedures of DTC and its participants. These procedures are the same as those that apply to any other securities that you hold in book entry or "street name" form.

Fund Share Trading Prices

The trading prices of Shares of the Fund on the Exchange may differ from the Fund's daily NAV. Market forces of supply and demand, economic conditions and other factors may affect the trading prices of Shares of the Fund.

The approximate value of Shares of the Fund, an amount representing on a per share basis the sum of the current market price of the cash or securities, as applicable, accepted by the Fund in exchange for Shares of the Fund and an estimated cash component, if any, is disseminated every 15 seconds throughout the trading day through the facilities of the Consolidated Tape Association. This approximate value should not be viewed as a "real-time" update of the NAV per Share of the Fund because the approximate value may not be calculated in the same manner as the NAV, which is computed once a day, generally at the end of the business day. The Fund is not involved in, or responsible for, the calculation or dissemination of the approximate value of the Fund Shares and the Fund does not make any warranty as to its accuracy.

Frequent Purchases and Redemptions of Fund Shares

Shares of the Fund may be purchased and redeemed directly from the Fund only in Creation Units by Authorized Participants. The vast majority of trading in Shares of the Fund occurs on the secondary market, and does not involve the Fund directly. In-kind purchases and redemptions of Creation Units by Authorized Participants and cash trades on the secondary market are unlikely to cause many of the harmful effects of frequent purchases and/or redemptions of Fund Shares. Cash purchases and/or redemptions of Creation Units, however, can result in disruption of portfolio management, dilution to the Fund and increased transaction costs, which could negatively impact the Fund's ability to achieve its investment objective, and may lead to the realization of capital gains. These consequences may increase as the frequency of cash purchases and redemptions of Creation Units by Authorized Participants increases. However, direct trading by Authorized Participants is critical to ensuring that Fund Shares trade at or close to NAV.

The Fund imposes no restrictions on the frequency of purchases and redemptions ("market timing"). To minimize these potential consequences of frequent purchases and redemptions of Fund Shares, the Fund employs fair valuation pricing, and imposes transaction fees on purchases and redemptions of Creation Units to cover the custodial and other costs the Fund incurs in effecting trades. In addition, the Adviser monitors trades by Authorized Participants for patterns of abusive trading and the Fund reserves the right to not accept orders from Authorized Participants that the Adviser has determined may be disruptive to the management of the Fund, or otherwise are not in the best interests of the Fund. For these reasons, the Board has not adopted policies and procedures with respect to frequent purchases and redemptions of Fund Shares. The Trust's policies and procedures regarding frequent purchases and redemptions may be modified by the Board of Trustees at any time.

The Trust's policies and procedures prohibit the practice of any officer or employee of the Trust, a Trust investment adviser (including any sub-adviser), the distributor, custodian, or transfer agent, or other affiliated person of the Trust placing orders to purchase or redeem shares of a series of the Trust after the designated time as of which the Fund calculates its NAV (i.e. "late trading").

Distribution and Service Plan

The Fund has adopted a distribution and service plan ("Plan") pursuant to Rule 12b-1 under the Investment Company Act. Under the Plan, the Fund is authorized to pay distribution fees to the Distributor and other firms that provide distribution and shareholder services ("Service Providers"). If a Service Provider provides such services, the Fund may pay fees at an annual rate not to exceed 0.25% of average daily net assets, pursuant to Rule 12b-1 under the Investment Company Act.

Fund Facts

No distribution or service fees are currently paid by the Fund, however, and there are no current plans to impose these fees. In the event Rule 12b-1 fees are charged, over time they would increase the cost of an investment in the Fund because they would be paid on an ongoing basis.

Fund Website and Disclosure of Portfolio Holdings

The Trust maintains a website for the Fund at www.calamos.com. Among other things, this website includes this Prospectus and the SAI, and will include the Fund's holdings, the Fund's last annual and semi-annual reports (when available), pricing information about Fund Shares trading on the Exchange, daily NAV calculations and a historical comparison of the trading prices to NAV.

Each day the Fund is open for business, the Trust publicly disseminates the Fund's full portfolio holdings as of the close of the previous day through its website at www.calamos.com. A description of the Trust's policies and procedures with respect to the disclosure of the Fund's portfolio holdings is available in the Fund's SAI.

Dividends, Other Distributions and Taxes

Fund Distributions

The Fund generally pays out dividends from its net investment income, if any, to shareholders monthly, and distributes its net capital gains, if any, to shareholders annually. The Fund typically earns dividends from stocks in which it invests. These amounts, net of expenses, are passed along to Fund shareholders as "income dividends." The Fund realizes capital gains or losses whenever it sells securities. Net long-term capital gains are distributed to shareholders as "capital gain dividends."

Brokers may make available to their customers who own Fund Shares the DTC book-entry dividend reinvestment service. To determine whether the dividend reinvestment service is available and whether there is a commission or other charge for using this service, consult your broker. Brokers may require Fund shareholders to adhere to specific procedures and timetables. If this service is available and used, dividend distributions of both income and net realized gains will be automatically reinvested in additional whole Fund Shares of the Fund purchased in the secondary market. Without this service, investors would receive their distributions in cash.

Taxes

As with any investment, you should consider how your investment in Fund Shares will be taxed. The tax information in this prospectus is provided only as general information. This section is current as of the date of this prospectus. Tax laws and interpretations change frequently, and these summaries do not describe all of the tax consequences to all taxpayers. For example, these summaries generally do not describe your situation if you are a corporation, a non-U.S. person, a broker-dealer, or other investor with special circumstances. However, with respect to certain tax issues, the summaries describe the general tax treatment of certain distributions made to corporations and non-U.S. persons. In addition, this section does not describe your state, local or non-U.S. tax consequences. You should consult your own tax advisor about the tax consequences of an investment in Fund Shares.

Fund distributions to you and the sale or redemption of your Fund Shares will have tax consequences to you. Such consequences may be different if you hold your Shares through a tax-exempt entity or tax-advantaged retirement account, such as an individual retirement account or 401(k) plan.

The Fund intends to elect to be treated, and intends to qualify each year, as a regulated investment company (a "RIC") under the Code. As a RIC, the Fund is generally not subject to corporate-level U.S. federal income tax on any net ordinary income or capital gains that are timely distributed to shareholders. However, the Fund's failure to qualify as a RIC or to meet minimum distribution requirements would result (if certain relief provisions were not available) in corporate-level taxation and, consequently, a reduction in amounts available for distribution to shareholders.

For purposes of the diversification tests, the identification of the issuer (or, in some cases, issuers) of a particular investment can depend on the terms and conditions of such investment. In particular, there is no published Internal Revenue Service guidance or case law on how to determine the "issuer" of various derivatives that the Fund may enter into. Therefore, there is a risk that the Fund will not meet the Code's diversification requirements and will not qualify, or will be disqualified, as a RIC.

Fund Facts

Taxes on Distributions

Distributions by the Fund generally are taxable to you as ordinary income or capital gains. Distributions are subject to federal income tax, whether received in cash or reinvested in additional Fund Shares or shares of another fund, and may be subject to state or local taxes. Distributions of the Fund's "investment company taxable income" generally will be taxable as ordinary income to the extent of the Fund's current or accumulated earnings and profits. Notwithstanding the foregoing, distributions that are attributable to "qualified dividends" received by the Fund may be eligible to be taxed at long-term capital gains rates, as long as the Fund and the shareholder meet certain holding period requirements.

Distributions of the Fund's net capital gain that are properly reported by the Fund as "capital gain dividends" will generally be taxable to you as long-term capital gains, currently at a maximum rate of 20%, regardless of your holding period in the Fund's Shares. Distributions in excess of the Fund's current and accumulated earnings and profits first will reduce your adjusted tax basis in your Fund Shares and, after the adjusted basis is reduced to zero, will constitute capital gain. Such capital gain will be long-term capital gain and thus, will be taxed at a maximum rate of 20%, if the distributions are attributable to Fund Shares that you have held for more than one year.

Certain non-corporate taxpayers will also be subject to a 3.8% U.S. federal Medicare contribution tax with respect to the lesser of (1) their "net investment income" or (2) the excess of their "modified adjusted gross income" over a threshold amount ($200,000 for single taxpayers and $250,000 for taxpayers who are married and filing jointly).

Corporate shareholders of the Fund are generally eligible for a dividends-received deduction with respect to ordinary income dividends (but not capital gain dividends) properly designated as eligible for such deduction by the Fund, as long as the Fund and the corporate shareholder meet certain holding period and other requirements.

Under a dividend reinvestment service, you may have the option to have all cash distributions automatically reinvested in additional Fund Shares. Any distributions reinvested under such a service will nevertheless be taxable to you as described above.

You will have an adjusted basis in the additional Fund Shares purchased through such a reinvestment service equal to the amount of the reinvested distribution plus the amount of any fees charged for the transaction. The additional Fund Shares will have a holding period commencing on the day following the day on which they are credited to your account.

A distribution will reduce the Fund's NAV per Share and generally will be taxable to you as ordinary income or capital gain even if it is paid from income or gains earned by the Fund before you invested in the Fund. From an investment standpoint, such a distribution constitutes a return of capital. However, from a tax standpoint, it constitutes taxable income. In general, distributions are subject to federal income tax as of the date of payment. However, distributions paid in January will be treated as paid on December 31 of the prior year if they were declared and payable to shareholders of record on a date in October, November or December of the prior year.

The Fund's investments in other investment companies (including ETFs) that qualify as RICs could affect the amount, timing and character of distributions from the fund, and therefore, may increase the amount of taxes payable by shareholders. In addition, the Fund's investments in certain debt instruments could cause the Fund to recognize taxable income in excess of the cash generated by such investments, which may require the Fund to dispose of other investments in order to make required distributions.

The Fund's transactions in derivatives, as well as its hedging, short sale, securities loan or similar transactions, if any, may be subject to one or more special tax rules. These rules may affect whether gains and losses recognized by the Fund are treated as ordinary or capital, accelerate the recognition of income or gains to the Fund, defer losses to the Fund, and cause adjustments in the holding periods of the Fund's securities, thereby affecting whether capital gains and losses are treated as short-term or long-term. These rules could therefore affect the amount, timing and/or character of distributions to shareholders and thus taxes payable by shareholders.

You may be subject to federal back-up withholding tax, if you do not provide the Fund with a taxpayer identification number (for an individual, a social security number) and make other required certifications, or the Internal Revenue Service informs the Fund that your tax identification number is incorrect. Backup withholding is not an additional tax. You may claim the amount

Fund Facts

withheld as a credit on your federal income tax return, provided you furnish the appropriate information to the Internal Revenue Service.

Taxes When Shares are Sold

Any capital gain or loss realized upon a sale of Fund Shares is generally treated as long-term capital gain or loss if you have held the Fund Shares for more than one year and as short-term capital gain or loss if you have held the Fund Shares for one year or less. The ability to deduct capital losses realized on a sale of Fund Shares may be limited.

Taxes on Purchase and Redemption of Creation Units

An Authorized Participant that exchanges equity securities for Creation Units will generally recognize a gain or a loss on the exchange. Any such gain or loss will be equal to the difference between the market value of the Creation Units at the time of the exchange, plus (or minus) the cash amount received (or paid), and such Authorized Participant's aggregate basis in the securities surrendered. A person who redeems Creation Units for equity securities will generally recognize a gain or loss equal to the difference between the aggregate market value of the securities received, plus (or minus) any cash received (or paid), and such person's basis in the Creation Units redeemed. The Internal Revenue Service, however, may assert that a loss realized upon an exchange of securities for Creation Units cannot be deducted currently under the rules governing "wash sales," or on the basis that there has been no significant change in the Authorized Participant's economic position with respect to such Creation Units. Persons exchanging securities should consult their own tax advisor with respect to the applicability of the wash sale rules and the availability and timing of a deduction for any loss. In addition, when a regulated investment company redeems a shareholder in kind, the regulated investment company generally is not required to recognize taxable gains in respect of the portfolio securities it distributes to the redeeming shareholder. However, the Fund may be required to recognize taxable gain on the distribution of certain securities, and the Internal Revenue Service may assert that the Fund must recognize taxable gain in respect of certain other securities that the Fund distributes to a shareholder in exchange for Creation Units, which may increase the amount of taxable gains that the Fund would otherwise be required to distribute in order to maintain its qualification as a regulated investment company and avoid a Fund-level tax.

Any capital gain or loss realized upon a redemption of Creation Units is generally treated as long-term capital gain or loss if the Creation Units have been held for more than one year and as short-term capital gain or loss if the Creation Units have been held for one year or less. If you purchase or redeem Creation Units, you will be sent a confirmation statement showing how many Fund Shares you purchased or sold and at what price.

Authorized Participants that are dealers may be subject to special tax rules and should consult their own tax advisors regarding the tax consequences of purchasing and redeeming Creation Units in their capacity as dealers.

Treatment of Fund Expenses

Expenses incurred and deducted by the Fund will generally not be treated as income taxable to you.

Non-U.S. Taxes

Income and proceeds received by the Fund from sources within foreign countries may be subject to withholding and other taxes imposed by such countries, which would reduce the Fund's return on investments in such countries. Tax treaties between certain countries and the U.S. may reduce or eliminate such taxes. Shareholders generally will not be entitled separately to claim a credit or deduction in respect of non-U.S. taxes paid or treated as paid by the Fund. In addition, the Fund's investments in foreign securities or foreign currencies may increase or accelerate the Fund's recognition of ordinary income and may affect the timing or amount of the Fund's distributions.

Non-U.S. Investors

If you are a non-U.S. investor (i.e., an investor other than a U.S. citizen or resident or a U.S. corporation, partnership, estate or trust), you should be aware that, generally, subject to applicable tax treaties, distributions from the Fund will be characterized as dividends for U.S. federal income tax purposes (other than dividends which the Fund properly reports as capital gain dividends) and will be subject to U.S. federal income taxes, including withholding taxes, subject to certain exceptions described below. However, distributions received by a non-U.S. investor from the Fund that are properly reported by the Fund as capital gain dividends may not be subject to U.S. federal income taxes, including withholding taxes, provided that the Fund makes

Fund Facts

certain elections and certain other conditions are met. Distributions from the Fund that are properly reported by the Fund as an interest-related dividend attributable to certain interest income received by the Fund or as a short-term capital gain dividend attributable to certain net short-term capital gain income received by the Fund may not be subject to U.S. federal income taxes, including withholding taxes when received by certain non-U.S. investors, provided that the Fund makes certain elections and certain other conditions are met.

Distributions may be subject to a U.S. withholding tax of 30% in the case of distributions to (i) certain non-U.S. financial institutions that have not entered into an agreement with the U.S. Treasury to collect and disclose certain information and are not resident in a jurisdiction that has entered into such an agreement with the U.S. Treasury and (ii) certain other non-U.S. entities that do not provide certain certifications and information about the entity's U.S. owners. The Internal Revenue Service and the Department of Treasury have issued proposed regulations providing that these withholding rules will not be applicable to the gross proceeds of share redemptions or capital gains dividends that the Fund pays.

Investments in Certain Non-U.S. Corporations

If the Fund holds an equity interest in any "passive foreign investment companies" ("PFICs"), which are generally certain non-U.S. corporations that receive at least 75% of their annual gross income from passive sources (such as interest, dividends, certain rents and royalties or capital gains) or that hold at least 50% of their assets in investments producing such passive income, the Fund could be subject to U.S. federal income tax and additional interest charges on gains and certain distributions with respect to those equity interests, even if all the income or gain is timely distributed to its shareholders. The Fund will not be able to pass through to its shareholders any credit or deduction for such taxes. The Fund may be able to make an election that could ameliorate these adverse tax consequences. For instance, the Fund may elect to mark the gains (and to a limited extent losses) in such holdings "to the market" as though it had sold (and, solely for purposes of this mark-to-market election, repurchased) its holdings in those PFICs on the last day of the Fund's taxable year. If the Fund were to make a mark-to-market election, it would recognize as ordinary income any increase in the value of such PFIC shares, and as ordinary loss any decrease in such value to the extent it did not exceed prior increases included in income. Under this election, the Fund might be required to recognize in a year income in excess of its distributions from PFICs and its proceeds from dispositions of PFIC stock during that year, and such income would nevertheless be subject to the distribution requirement and would be taken into account for purposes of the 4% excise tax that may be imposed on the undistributed income of a RIC. Dividends paid by PFICs are not treated as qualified dividend income.

Other Tax Matters

The foregoing is only a summary of certain federal income tax considerations of investing in the Fund under current law, which is subject to change in the future. Shareholders who are not U.S. persons within the meaning of the Code, such as non-resident aliens, foreign trusts or estates, or foreign corporations or partnerships may be subject to different U.S. federal income tax treatment.

You may also be subject to state and local taxes on distributions paid by the Fund, and sales and redemptions of Fund Shares. You should consult your tax advisor for further information regarding federal, state, local and/or foreign tax consequences relevant to your specific tax situation. More information about taxes can be found in the Fund's SAI.

Net Asset Value

The NAV of shares is determined at the close of regular trading on the New York Stock Exchange (normally 4:00 p.m. Eastern Time) on each day the New York Stock Exchange ("NYSE") is open. NAV is computed by determining the aggregate market value of all assets of the Fund, less its liabilities, divided by the total number of shares outstanding ((assets-liabilities)/number of shares = NAV). The NYSE is closed on weekends and New Year's Day, Martin Luther King, Jr. Day, Presidents' Day, Good Friday, Memorial Day, Juneteenth National Independence Day, Independence Day, Labor Day, Thanksgiving Day and Christmas Day. The NAV takes into account the expenses and fees of the Fund, including management fees, which are accrued daily. The determination of NAV for the Fund for a particular day is applicable to all applications for the purchase of shares, as well as all requests for the redemption of shares, received by the Fund (or an authorized broker or agent, or its authorized designee) before the close of trading on the NYSE on that day.

Fund Facts

Generally, securities traded or dealt in upon one or more securities exchanges (whether domestic or foreign) for which market quotations are readily available and not subject to restrictions against resale shall be valued at the last quoted sales price on the primary exchange or, in the absence of a sale on the primary exchange, at the mean between the current bid and ask prices on such exchange. Securities primarily traded in the National Association of Securities Dealers' Automated Quotation System ("NASDAQ") National Market System for which market quotations are readily available shall be valued using the NASDAQ official closing price. Securities that are not traded or dealt in any securities exchange (whether domestic or foreign) and for which over-the-counter market quotations are readily available generally shall be valued at the last sale price or, in the absence of a sale, at the mean between the current bid and ask price on such over-the-counter market. Debt securities not traded on an exchange may be valued at prices supplied by a pricing agent(s) based on broker or dealer supplied valuations or matrix pricing, a method of valuing securities by reference to the value of other securities with similar characteristics, such as rating, interest rate and maturity. Futures, swaps and options contracts listed for trading on a futures or options exchange or board of trade for which market quotations are generally available are valued at the last quoted sale price, or, in the absence of a sale, at the mean of the last bid and ask price. Total return swaps on exchange-listed securities are valued at the last quoted sale price, or, in the absence of a sale, at the mean of the last bid and ask price.

Securities held by the Fund are valued in accordance with policies and procedures established by the Adviser pursuant to Rule 2a-5 under the Investment Company Act of 1940 ("1940 Act") and approved by and subject to the oversight of the Board of Trustees ("Valuation Procedures"). If market quotations are not readily available, securities or other assets will be valued at their fair value as determined in good faith by the Adviser in accordance with procedures approved by the Board and evaluated by the Board as to the reliability of the fair value method used. In these cases, the Fund's NAV will reflect certain portfolio securities' fair values rather than their market prices. Fair value pricing involves subjective judgments, and it is possible that the fair value determined for a security or other asset may be materially different than the value that could be realized upon the sale of that security or other asset. The fair value prices can differ from market prices. The Board of Trustees has designated Calamos Advisors as "valuation designee" for the Fund. The valuation designee is responsible for determining the value of the Fund's investments. The designee may also enlist third party consultants such as an audit firm or financial officer of a security issuer on an as-needed basis to assist in determining a security-specific fair value. The Board reviews and ratifies the execution of this process and the resultant fair value prices at least quarterly to assure the process produces reliable results.

The Fund may use independent pricing services to assist in calculating the value of the Fund's securities or other assets.

With respect to any portion of the Fund's assets that are invested in one or more open-end management investment companies registered under the 1940 Act, the Fund's net asset value is calculated based upon the net asset values of those open-end management investment companies, and the prospectuses for these companies explain the circumstances under which those companies will use fair value pricing and the effects of using fair value pricing.

Fund Service Providers

State Street Bank and Trust Company ("State Street"), located at One Congress Street, Suite 1, Boston, Massachusetts 02114-2016, serves as the Fund's administrator, custodian, fund accounting and financial accounting agent, and transfer agent.

Calamos Financial Services LLC ("CFS"), located at 2020 Calamos Court, Naperville, Illinois 60563, serves as the distributor of Creation Units for the Fund on an agency basis. The Distributor does not maintain a secondary market in Fund Shares.

Ropes & Gray LLP, located at 191 North Wacker Drive, 32^nd​ Floor, Chicago, IL 60606, serves as legal counsel to the Trust.

Premium/Discount Information

Information showing the number of days the market price of the Fund Shares was greater (at a premium) and less (at a discount) than the Fund's NAV for the most recently completed calendar year, and the most recently completed calendar quarters since that year (or the life of the Fund, if shorter), is available at www.calamos.com.

Fund Facts

Investments by Other Investment Companies

Section 12(d)(1) of the 1940 Act restricts investments by investment companies in the securities of other investment companies, including Fund Shares. Rule 12d1-4 under the 1940 Act permits investment companies ("acquiring funds") to invest in other investment companies ("acquired funds") beyond the limits of Section 12(d)(1), subject to certain terms and conditions. However, because more than 10% of the Fund's total assets may be invested in securities of other investment companies, including ETFs, other investment companies are not permitted to rely on Rule 12d1-4 to invest in the Fund in excess of the limits of Section 12(d)(1). To this end, Rule 12d1-4 relief from Section 12(d)(1) is not available for investments in the Fund, since this Fund operates as a "fund of funds."

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Financial Highlights

The financial highlights table is intended to help you understand the Fund's financial performance for the period of February 13, 2024 (commencement of operations) through July 31, 2024. Certain information reflects financial results for a single Fund share. The total returns in the table represent the rate that an investor would have earned (or lost) on an investment in the Fund (assuming reinvestment of all dividends and distributions). This information has been audited by Deloitte & Touche LLP, whose report, along with the Fund's financial statements, are included in the SAI, which is available upon request.

FINANCIAL HIGHLIGHTS

Selected data for a share outstanding throughout the period was as follows:

  •  Commencement of operations.

  (a)  Net investment income (loss) allocated based on average shares method.

  (b)  Distribution for annual periods determined in accordance with federal income tax regulations.

  (c)  Total return measures net investment income (loss) and capital gain or loss from portfolio investments assuming reinvestment of dividends and capital gains distributions. Total return is not annualized for periods that are less than a full year and does not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

  (d)  Annualized.

  (e)  Not annualized.

  (f)  Portfolio turnover rate excludes securities received or delivered from in-kind processing of creations or redemptions.

Other Information

Continuous Offering

The method by which Creation Units of Fund Shares are created and traded may raise certain issues under applicable securities laws. Because new Creation Units of Fund Shares are issued and sold by the Fund on an ongoing basis, a "distribution," as such term is used in the Securities Act of 1933, as amended (the "Securities Act"), may occur at any point. Broker-dealers and other persons are cautioned that some activities on their part may, depending on the circumstances, result in their being deemed participants in a distribution in a manner which could render them statutory underwriters and subject them to the prospectus delivery requirements and liability provisions of the Securities Act. For example, a broker-dealer firm or its client may be deemed a statutory underwriter if it takes Creation Units after placing an order with the Distributor, breaks them down into constituent Fund Shares and sells the Fund Shares directly to customers or if it chooses to couple the creation of a supply of new Fund Shares with an active selling effort involving solicitation of secondary market demand for Fund Shares. A determination of whether one is an underwriter for purposes of the Securities Act must take into account all the facts and circumstances pertaining to the activities of the broker-dealer or its client in the particular case, and the examples mentioned above should not be considered a complete description of all the activities that could lead to a characterization as an underwriter.

Broker-dealer firms should also note that dealers who are not "underwriters" but are effecting transactions in Fund Shares, whether or not participating in the distribution of Fund Shares, are generally required to deliver a prospectus. This is because the prospectus delivery exemption in Section 4(3) of the Securities Act is not available in respect of such transactions as a result of Section 24(d) of the Investment Company Act of 1940, as amended (the "Investment Company Act"). As a result, broker-dealer firms should note that dealers who are not "underwriters" but are participating in a distribution (as contrasted with engaging in ordinary secondary market transactions) and thus dealing with the Fund Shares that are part of an overallotment within the meaning of Section 4(3)(C) of the Securities Act, will be unable to take advantage of the prospectus delivery exemption provided by Section 4(3) of the Securities Act. For delivery of prospectuses to exchange members, the prospectus delivery mechanism of Rule 153 under the Securities Act is only available with respect to transactions on a national exchange.

Disclaimers

Nasdaq^®​, Nasdaq-100^®​, Nasdaq-100 Index^®​, and QQQ^®​ are registered trademarks of Nasdaq, Inc. (which with its affiliates is referred to as the "Corporations") and are licensed for use by Calamos Advisors LLC. The Product(s) have not been passed on by the Corporations as to their legality or suitability. The Product(s) are not issued, endorsed, sold, or promoted by the Corporations. The Corporations make no warranties and bear no liability with respect to the product(s).

Summary of Certain Provisions of the Second Amended and Restated Trust Instrument

The summary below is a synopsis of certain provisions contained in the Trust's Second Amended and Restated Trust Instrument (the "Trust Instrument"). Shareholders should refer to the Trust Instrument for further information. Defined terms have the meanings contained in the Trust Instrument.

Derivative Actions

The Second Amended and Restated Trust Instrument (the "Trust Instrument") requires, within Section 9 of Article IV, that before bringing any derivative action on behalf of the Fund, Shareholders must have made a written demand to the Board of Trustees requesting that they cause the Trust or affected Series or Class, as applicable, to file the action itself.

In order to warrant consideration, any such written demand must include at least the following:

(1)  a detailed description of the action or failure to act complained of and the facts upon which each such allegation is made;

(2)  a statement to the effect that the complaining Shareholders believe that they will fairly and adequately represent the interests of similarly situated Shareholders in enforcing the right of the Trust or the affected Series or Class, as applicable and an explanation of why the complaining Shareholders believe that to be the case;

Other Information

(3)  a certification that the following requirements have been met, as well as information reasonably designed to allow the Trustees to verify that certification:

(a)  each complaining Shareholder was a Shareholder of the Trust or the affected Series or Class, as applicable, at the time of the action or failure to act complained of, or acquired the Shares afterwards by operation of law from a Person who was a Shareholder at that time; and

(b)  each complaining Shareholder was a Shareholder of the Trust or the affected Series or Class, as applicable, as of the time the demand required by Section 9 of Article IV was made; and

(4)  a certification that each complaining Shareholder will be a Shareholder of the Trust or the affected Series or Class, as applicable as of the commencement of the derivative action.

The Trust Instrument further provides that at least 10% of the Shareholders of the Trust or the affected Series or Class, as applicable, must join in bringing the derivative action. This provision does not apply to claims brought under the federal securities laws.

The Trust Instrument also provides that a copy of the derivative complaint must be served on the Trust, assuming the requirements described above have already been met and the derivative action has not been barred as further described in the Trust Instrument.

Forum and Waiver of Jury Trial

Section 10 of Article X of the Trust Instrument outlines which shareholder actions must be brought in state court and which must be brought in federal court. This section states in particular that, unless the Trust consents in writing to the selection of an alternative forum, the Federal District Courts of the United States of America shall be the sole and exclusive forum for the resolution of any complaint asserting a cause of action arising under any federal securities law. This provision may increase costs for a shareholder to bring a claim or may limit a shareholder's ability to bring a claim in a judicial forum that they find more convenient or favorable. While the enforceability of the exclusive forum provisions may be challenged, this section also provides that if any provisions of Section 10 shall be held to be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining portions will still apply.

Section 10 of Article X of the Trust Instrument also states that shareholders and all other such persons bringing any such suit, action, or proceeding in the Superior Court in the State of Delaware waive the right to a trial by jury to the fullest extent permitted by law.

For more detailed information on the Fund, several additional sources of information are available to you. The Fund's SAI, incorporated by reference into this prospectus, contains detailed information on the Fund's policies and operation. Additional information about the Fund's investments is available in the annual and semi-annual reports to shareholders. In the Fund's annual reports, you will find a discussion of the market conditions and investment strategies that significantly impacted the Fund's performance during the last fiscal year. The Fund's most recent SAI, annual or semi-annual reports and certain other information are available free of charge by calling the Fund at (866) 363-9219, on the Fund's website at www.calamos.com or through your financial advisor. Shareholders may call the toll-free number above with any inquiries.

You may obtain this and other information regarding the Fund, including the SAI and Codes of Ethics adopted by the Adviser, Distributor and the Trust, directly from the SEC. Information on the SEC's website is free of charge. Visit the SEC's on-line EDGAR database at http://www.sec.gov. You may also request information regarding the Fund by sending a request (along with a duplication fee) to the SEC by sending an electronic request to [email protected].

Calamos Alternative
Nasdaq^®​ & Bond ETF

2020 Calamos Court
Naperville, IL 60563-2787
866.363.9219

www.calamos.com

SEC File #333-191151
#811-22887

CANQSTAPRO 120224

Dated December 2, 2024

STATEMENT OF ADDITIONAL INFORMATION

2020 Calamos Court
Naperville, Illinois 60563
866.363.9219

This Statement of Additional Information ("SAI") is not a prospectus. It should be read in conjunction with the prospectus dated December 2, 2024, as it may be revised from time to time (the "Prospectus"), for the Calamos Convertible Equity Alternative ETF (the "Fund"), a series of the Calamos ETF Trust (the "Trust"). Capitalized terms used herein that are not defined have the same meanings as in the Prospectus, unless otherwise noted. A copy of the Prospectus may be obtained without charge by calling the Fund at (866) 363-9219, visiting the Fund's website at www.calamos.com or through your financial advisor.

References to the Investment Company Act of 1940, as amended (the "1940 Act"), or other applicable law, will include any rules promulgated thereunder and any guidance, interpretations or modifications by the Securities and Exchange Commission (the "SEC"), SEC staff or other authority with appropriate jurisdiction, including court interpretations, and exemptive, no action or other relief or permission from the SEC, SEC staff or other authority.

CVRTSAI 120224

TABLE OF CONTENTS

THE TRUST AND THE FUND

The Trust was organized as a Delaware statutory trust on June 17, 2013. The Trust is an open-end, registered management investment company. The Trust currently offers shares in twenty-nine series of the Trust. Series other than the Fund are offered through separate prospectuses and statements of additional information and are not further discussed herein. The offering of the Fund's shares ("Shares") is registered under the Securities Act of 1933, as amended (the "Securities Act").

The Fund is a non-diversified, actively managed exchange-traded fund. The Fund offers and issues Shares at net asset value ("NAV") only in aggregations of a specified number of Shares, generally in exchange for a basket of securities constituting the portfolio holdings of the Fund, together with the deposit of a specified cash payment, or, in certain circumstances, for an all cash payment. Shares of the Fund will be listed and principally traded on NYSE Arca, Inc. ("NYSE Arca" or the "Exchange"). Shares will trade on the Exchange at market prices that may be below, at, or above NAV. Unlike mutual funds, Fund Shares are not individually redeemable securities. Rather, the Fund issues and redeems Shares on a continuous basis at NAV, only in creation units of 50,000 Shares (each, a "Creation Unit"). In the event of the liquidation of the Fund, the Trust may lower the number of Shares in a Creation Unit. Financial entities known as "authorized participants" (which are discussed in greater detail below) have contractual arrangements with the Fund or the Distributor to purchase and redeem Fund Shares directly with the Fund in Creation Units in exchange for the securities comprising the Fund and/or cash, or some combination thereof. Fund Shares are traded in the secondary market and elsewhere at market prices that may be at, above, or below the Fund's NAV. Fund Shares are only redeemable in Creation Units by authorized participants. An authorized participant that purchases a Creation Unit of Fund Shares deposits with the Fund a "basket" of securities and/or other assets identified by the Fund that day, and then receives the Creation Unit of Fund Shares in return for those assets. The redemption process is the reverse of the purchase process: the authorized participant redeems a Creation Unit of Fund Shares for a basket of securities and other assets. The basket is generally representative of the Fund's portfolio, and together with a cash balancing amount, it is equal to the NAV of the Fund Shares comprising the Creation Unit. Pursuant to Rule 6c-11 of the 1940 Act ("Rule 6c-11"), the Fund may utilize baskets that are not representative of the Fund's portfolio. Such "custom baskets" are discussed in the section entitled "Creations and Redemptions of Creation Units." Transaction fees and other costs associated with creations or redemptions that include cash may be higher than the transaction fees and other costs associated with in-kind creations or redemptions. In all cases, conditions with respect to creations and redemptions of shares and fees will be limited in accordance with the requirements of SEC rules and regulations applicable to management investment companies offering redeemable securities.

Unlike index-based ETFs, the Fund is "actively managed" and does not seek to replicate the performance of a specified index.

The Board of Trustees of the Trust (the "Board of Trustees" or the "Trustees") has the right to establish additional series in the future, to determine the preferences, voting powers, rights and privileges thereof and to modify such preferences, voting powers, rights and privileges without shareholder approval. Shares of any series may also be divided into one or more classes at the discretion of the Trustees. The Trust or any series or class thereof may be terminated at any time by the Board of Trustees upon written notice to the shareholders.

EXCHANGE LISTING AND TRADING

Shares of the Fund are listed and traded on the NYSE Arca. Shares trade on the Exchange or in secondary markets at prices that may differ from their NAV or Intraday Indicative Value ("IIV"), because such prices may be affected by market forces (such as supply and demand for Shares). As is the case of other securities traded on an exchange, when you buy or sell Shares on the Exchange or in the secondary markets your broker will normally charge you a commission or other transaction charges. Further, the Trust reserves the right to adjust the price of Shares in the future to maintain convenient trading ranges for investors (namely, to maintain a price per Share that is attractive to investors) by share splits or reverse share splits, which would have no effect on the NAV.

There can be no assurance that the requirements of the Exchange necessary to maintain the listing of Shares of the Fund will continue to be met. The Exchange may, but is not required to, remove the Fund Shares from listing if, among other things: (i) following the initial 12-month period beginning upon the commencement of trading of Fund Shares, there are fewer than 50 record and/or beneficial owners of Fund Shares; (ii) a Fund is no longer eligible to operate in reliance on Rule 6c-11; (iii) any of the other listing requirements are not continuously maintained; or (iv) any event shall occur or condition shall exist that, in the opinion of the Exchange, makes further dealings on the Exchange inadvisable. The Exchange will remove the Shares of the Fund from listing and trading upon termination of the Fund.

The Fund is not sponsored, endorsed, sold or promoted by the Exchange. The Exchange makes no representation or warranty, express or implied, to the owners of Shares of the Fund or any member of the public regarding the advisability of investing in securities generally or in the Fund particularly or the ability of the Fund to achieve its objectives. The Exchange has no obligation or liability in connection with the administration, marketing or trading of the Fund.

DISCLOSURE OF PORTFOLIO HOLDINGS

The Board has adopted a policy regarding the disclosure of information about the Fund's portfolio securities. Under the policy, portfolio holdings of the Fund, which will form the basis for the calculation of NAV on any day on which the Trust is open for business ("Business Day"), are publicly disseminated prior to the opening of trading on the Exchange that Business Day through financial reporting or news services, including the website www.calamos.com. In addition, each Business Day a portfolio composition file, which displays the basket of securities to be deposited to purchase Creation Units of the Fund ("In-Kind Creation Basket") and the amount of cash necessary to equal the difference between the NAV of a Creation Unit and the market value of the In-Kind Creation Basket ("Cash Component"), is publicly disseminated prior to the opening of the Exchange via the National Securities Clearing Corporation ("NSCC").

INVESTMENT OBJECTIVE

The Calamos Convertible Equity Alternative ETF's investment objective is total return through capital appreciation and current income.

The Fund's investment objective is non-fundamental and may be changed by a vote of the Fund's Board, without shareholder approval.

The Fund has adopted a non-fundamental operating policy that requires it, under normal circumstances, to invest at least 80% of the Fund's net assets (plus borrowings for investment purposes, if any) in convertible securities (including synthetic convertible instruments). Although these requirements may be changed by the Board of Trustees without shareholder approval, the Fund will notify shareholders in writing at least 60 days prior to any change in its 80% policy.

INVESTMENT PRACTICES

The prospectus contains information concerning the Fund's investment objective and principal investment strategies and risks. This Statement of Additional Information provides additional information concerning certain securities and strategies used by the Fund and their associated risks.

In pursuing its investment objective, the Fund will invest as described below and in the Fund's prospectus. The table below indicates whether the Fund, directly or indirectly through its investment in the underlying funds, invests in the securities and instruments listed as part of its principal (P) or non-principal (N) investment strategies.

Unless otherwise noted, all investment policies and restrictions described in the Prospectus and Statement of Additional Information are measured at the time of the transaction in the security. If market action affecting fund securities (including, but not limited to, appreciation, depreciation, or a credit rating event) causes the Fund to exceed an investment policy or restriction, Calamos Advisors LLC ("Calamos Advisors" or the "Adviser") is not required to take immediate action. Under normal market conditions, however, Calamos Advisors will not make any acquisitions that will make the Fund further outside the investment restriction.