Form 497K LOOMIS SAYLES FUNDS I

Before you invest, you may want to review the Fund’s Prospectus, which contains more information about the Fund and its risks. You can find the Fund’s Prospectus, reports to shareholders, and other information about the Fund online at im.natixis.com/fund-documents. You can also get this information at no cost by calling 800-225-5478 or by sending an e-mail request to [email protected]. The Fund’s Prospectus and Statement of Additional Information, each dated February 1, 2023, as may be revised or supplemented from time to time, are incorporated by reference into this Summary Prospectus.

Investment Goal

The Fund’s investment objective is above-average total return through a combination of current income and capital appreciation.

Fund Fees & Expenses

The following table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in the Natixis Funds Complex. More information about these and other discounts is available from your financial professional and in the section “How Sales Charges Are Calculated” on page 56 of the Prospectus, in Appendix A to the Prospectus and on page 114 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).

Shareholder Fees

Annual Fund Operating Expenses

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The

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Fund Summary 

example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same, except that the example is based on the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement assuming that such waiver and/or reimbursement will only be in place through the date noted above and on the Total Annual Fund Operating Expenses for the remaining periods. The example for Class C shares for the ten-year period reflects the conversion to Class A shares after eight years. The example does not take into account brokerage commissions and other fees to financial intermediaries that you may pay on your purchases and sales of shares of the Fund. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 144% of the average value of its portfolio. 

Investments, Risks and Performance

Principal Investment Strategies

Under normal circumstances, the Fund will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in fixed-income securities (for example, bonds and other investments that Loomis Sayles believes have similar economic characteristics, such as notes, debentures and loans). It is anticipated that the Fund’s weighted average duration will generally be between two and five years. Duration is a measure of the expected life of a fixed-income security that is used to determine the sensitivity of a security’s price to changes in interest rates. A fund with a longer average portfolio duration will be more sensitive to changes in interest rates than a fund with a shorter average portfolio duration. By way of example, the price of a bond fund with an average duration of five years would be expected to fall approximately 5% if interest rates rose by one percentage point.

The Fund will purchase only investment-grade fixed-income securities, which are those securities that are rated in one of the top four rating categories at the time of purchase by at least one of the three major ratings agencies (Moody’s Investors Service, Inc., Fitch Investor Services, Inc. or S&P Global Ratings) or, if unrated, are determined by Loomis Sayles to be of comparable quality. The Fund may continue to hold up to 10% of its net assets in securities that are downgraded to a rating below investment-grade subsequent to their purchase if Loomis Sayles believes it is appropriate to do so.

In deciding which securities to buy and sell, Loomis Sayles may consider a number of factors related to the bond issue and the current bond market including, for example, the stability and volatility of a country’s bond markets, the financial strength of the issuer, current interest rates, current valuations, Loomis Sayles’ expectations regarding general trends in interest rates and currency considerations. Loomis Sayles will also consider how purchasing or selling a bond would impact the overall portfolio’s risk profile (for example, its sensitivity to currency risk, interest rate risk and sector-specific risk) and potential return (income and capital gains).

Three themes typically drive the Fund’s investment approach. First, Loomis Sayles generally seeks fixed-income securities that are attractively valued relative to the Loomis Sayles’ credit research team’s assessment of credit risk. The broad coverage combined with the objective of identifying attractive investment opportunities makes this an important component of the investment approach. Second, the Fund may invest significantly in securities the prices of which Loomis Sayles believes are more sensitive to events related to the underlying issuer than to changes in general interest rates or overall market default rates. These securities may not have a direct correlation with changes in interest rates, thus helping to manage interest rate risk and to offer diversified sources for return. Third, Loomis Sayles analyzes different sectors of the economy and differences in the yields (“spreads”) of various fixed-income securities in an effort to find securities that it believes may produce attractive returns for the Fund in comparison to their risk.

The Fund may invest up to 20% of its assets in U.S. dollar-denominated foreign securities, including emerging market securities. The Fund may invest without limit in obligations of supranational entities (e.g., the World Bank). Although certain securities purchased by the Fund may be issued by domestic companies incorporated outside of the United States, the Adviser does not consider these securities to be foreign if the issuer is included in the U.S. fixed-income indices published by Bloomberg. The Fund may also invest in mortgage-related securities, including mortgage dollar rolls. The Fund may also engage in futures transactions for hedging and investment purposes.

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Fund Summary 

The fixed-income securities in which the Fund may invest include, among other things, corporate bond and other debt securities (including junior and senior bonds), U.S. government securities, zero-coupon securities, collateralized loan obligations, mortgage-backed securities and other asset-backed securities, real estate investment trusts (“REITs”) and securities issued pursuant to Rule 144A under the Securities Act of 1933 (“Rule 144A securities”).

The Fund may also engage in active and frequent trading of securities. Frequent trading may produce a high level of taxable gains, including short-term capital gains taxable as ordinary income, as well as increased trading costs, which may lower the Fund’s return.

Principal Investment Risks

The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund. 

Fund shares are not bank deposits and are not guaranteed, endorsed or insured by the Federal Deposit Insurance Corporation or any other government agency, and are subject to investment risks, including possible loss of the principal invested.

The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund’s portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund.

Interest Rate Risk: Interest rate risk is the risk that the value of the Fund’s investments will fall if interest rates rise. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise.  Interest rate risk generally is greater for funds that invest in fixed-income securities with relatively longer durations than for funds that invest in fixed-income securities with shorter durations. The values of zero-coupon bonds may be more sensitive to fluctuations in interest rates than other fixed-income securities. In addition, an economic downturn or period of rising interest rates could adversely affect the market for these securities and reduce the Fund’s ability to sell them, negatively impacting the performance of the Fund. Potential future changes in government and/or central bank monetary policy and action may also affect the level of interest rates. Recently, there have been inflationary price movements, which have caused the fixed income securities markets to experience heightened levels of interest volatility and liquidity risk. The risks associated with rising interest rates may be particularly acute because of recent monetary policy measures.

Credit/Counterparty Risk: Credit/counterparty risk is the risk that the issuer or guarantor of a fixed-income security, or the counterparty to a derivative or other transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations. As a result, the Fund may sustain losses or be unable or delayed in its ability to realize gains. The Fund will be subject to credit/counterparty risk with respect to the counterparties to its derivatives transactions. This risk will be heightened to the extent the Fund enters into derivative transactions with a single counterparty (or affiliated counterparties that are part of the same organization), causing the Fund to have significant exposure to such counterparty. Many of the protections afforded to participants on organized exchanges and clearing houses, such as the performance guarantee given by a central clearing house, are not available in connection with over-the-counter (“OTC”) derivatives transactions, such as foreign currency transactions. For centrally cleared derivatives, such as cleared swaps, futures and many options, the primary credit/counterparty risk is the creditworthiness of the Fund’s clearing broker and the central clearing house itself. 

Mortgage-Related and Asset-Backed Securities Risk: In addition to the risks associated with investments in fixed-income securities generally (for example, credit, liquidity, inflation and valuation risk), mortgage-related and asset-backed securities are subject to the risks of the mortgages and assets underlying the securities as well as prepayment risk, the risk that the securities may be prepaid and result in the reinvestment of the prepaid amounts in securities with lower yields than the prepaid obligations. Conversely, there is a risk that a rise in interest rates will extend the life of a mortgage-related or asset-backed security beyond the expected prepayment time, typically reducing the security’s value, which is called extension risk. The Fund also may incur a loss when there is a prepayment of securities that were purchased at a premium. The Fund’s investments in other asset-backed securities are subject to risks similar to those associated with mortgage-related securities, as well as additional risks associated with the nature of the assets and the servicing of those assets.

Market/Issuer Risk: The market value of the Fund’s investments will move up and down, sometimes rapidly and unpredictably, based upon overall market and economic conditions, as well as a number of reasons that directly relate to the issuers of the Fund’s investments, such as management performance, financial condition and demand for the issuers’ goods and services.

Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit/counterparty and information risks. The Fund’s investments in foreign securities also are subject to foreign currency fluctuations and other foreign currency-related risks. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity.

Below Investment Grade Fixed-Income Securities Risk: The Fund’s investments in below investment grade fixed-income securities, also known as “junk bonds,” may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit/counterparty risk (including a greater risk of default) and liquidity risk. The ability of the issuer to make principal and interest payments is predominantly speculative for below investment grade fixed-income securities.

Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may be subject to currency risk because it may invest in securities or other instruments denominated in, or that generate income denominated in, foreign currencies. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. 

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Fund Summary 

Cybersecurity and Technology Risk: The Fund, its service providers, and other market participants increasingly depend on complex information technology and communications systems, which are subject to a number of different threats and risks that could adversely affect the Fund and its shareholders. Cybersecurity and other operational and technology issues may result in financial losses to the Fund and its shareholders.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including futures transactions) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities market values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those that would have occurred had derivatives not been used. The Fund’s use of derivatives involves other risks, such as credit/counterparty risk relating to the other party to a derivative contract (which is greater for OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than the initial margin (if any) required to initiate derivatives positions. There is also the risk that the Fund may be unable to terminate or sell a derivative position at an advantageous time or price. The Fund’s derivative counterparties may experience financial difficulties or otherwise be unwilling or unable to honor their obligations, possibly resulting in losses to the Fund.

Emerging Markets Risk: In addition to the risks of investing in foreign investments generally, emerging markets investments are subject to greater risks arising from political or economic instability, war, nationalization or confiscatory taxation, currency exchange or repatriation restrictions, sanctions by other countries (such as the United States or the European Union, new or inconsistent government treatment of or restrictions on issuers and instruments,) and an issuer’s unwillingness or inability to make dividend, principal or interest payments on its securities. Emerging markets companies may be smaller and have shorter operating histories than companies in developed markets.

Large Investor Risk: Ownership of shares of the Fund may be concentrated in one or a few large investors. Such investors may redeem shares in large quantities or on a frequent basis. Redemptions by a large investor can affect the performance of the Fund, may increase realized capital gains, including short-term capital gains taxable as ordinary income, may accelerate the realization of taxable income to shareholders and may increase transaction costs. These transactions potentially limit the use of any capital loss carryforwards and certain other losses to offset future realized capital gains (if any). Such transactions may also increase the Fund’s expenses.

Leverage Risk: Leverage is the risk associated with securities or investment practices (e.g., borrowing and the use of certain derivatives) that multiply small index, market or asset-price movements into larger changes in value. The use of leverage increases the impact of gains and losses on the Fund’s returns, and may lead to significant losses if investments are not successful.

Liquidity Risk: Liquidity risk is the risk that the Fund may be unable to find a buyer for its investments when it seeks to sell them or to receive the price it expects. Decreases in the number of financial institutions willing to make markets in the Fund’s investments or in their capacity or willingness to transact may increase the Fund’s exposure to this risk. Events that may lead to increased redemptions, such as market disruptions or increases in interest rates, may also negatively impact the liquidity of the Fund’s investments when it needs to dispose of them. If the Fund is forced to sell its investments at an unfavorable time and/or under adverse conditions in order to meet redemption requests, such sales could negatively affect the Fund. During times of market turmoil, there may be no buyers or sellers for securities in certain asset classes. Securities acquired in a private placement, such as Rule 144A securities, are generally subject to significant liquidity risk because they are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. In other circumstances, liquid investments may become illiquid.  Derivatives, and particularly OTC derivatives, are generally subject to liquidity risk as well. Liquidity issues may also make it difficult to value the Fund’s investments. The Fund may invest in liquid investments that become illiquid due to financial distress, or geopolitical events such as sanctions, trading halts or wars.

Management Risk: A strategy used by the Fund’s portfolio managers may fail to produce the intended result. 

REITs Risk: Investments in the real estate industry, including REITs, are particularly sensitive to economic downturns and are sensitive to factors such as changes in real estate values, property taxes and tax laws, interest rates, cash flow of underlying real estate assets, occupancy rates, government regulations affecting zoning, land use and rents and the management skill and creditworthiness of the issuer. Companies in the real estate industry also may be subject to liabilities under environmental and hazardous waste laws. In addition, the value of a REIT is affected by changes in the value of the properties owned by the REIT or mortgage loans held by the REIT. REITs are also subject to default and prepayment risk. Many REITs are highly leveraged, increasing their risk. The Fund will indirectly bear its proportionate share of expenses, including management fees, paid by each REIT in which it invests in addition to the expenses of the Fund.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year, ten-year and life-of-class periods (as applicable) compare to those of a broad measure of market performance.  Class C shares will automatically convert to Class A shares after eight years. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at im.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

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Fund Summary 

The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.

Total Returns for Class Y Shares

Effective August 31, 2016, the Fund’s Retail Class shares and Institutional Class shares were redesignated as Class A shares and Class Y shares, respectively. Accordingly, the returns shown in the table for Class A shares prior to August 31, 2016 are those of Retail Class shares, restated to reflect the sales loads of Class A shares, and the returns in the table for Class Y shares prior to August 31, 2016 are those of Institutional Class shares. Prior to the inception of Class C shares (August 31, 2016), performance is that of Retail Class shares, restated to reflect the higher net expenses and sales loads of Class C shares.

The Fund did not have Class T shares outstanding during the periods shown above. The returns of Class T shares would have been substantially similar to the returns of the Fund’s other share classes because they would have been invested in the same portfolio of securities and would only differ to the extent the other share classes did not have the same expenses. Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T shares.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes The Return After Taxes on Distributions and Sale of Fund Shares for the 1-year period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period.

Management

Investment Adviser

Loomis Sayles

Portfolio Managers

Daniel Conklin, CFA^®, Vice President of Loomis Sayles, served as associate portfolio manager of the Fund from 2019 to 2020 and has served as co-portfolio manager of the Fund since 2020.

Christopher T. Harms, Vice President of Loomis Sayles, has served as a portfolio manager of the Fund since 2012.

Clifton V. Rowe, CFA^®, Vice President of Loomis Sayles, has served as a portfolio manager of the Fund since 2005.

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Fund Summary 

Purchase and Sale of Fund Shares

Class A and C Shares

The following chart shows the investment minimums for various types of accounts:

There is no initial or subsequent investment minimum for:

The minimum investment requirements for Class A shares may be waived or lowered for investments effected through certain financial intermediaries that have entered into special arrangements with Natixis Distribution, LLC (the “Distributor”). Consult your financial intermediary for additional information regarding the minimum investment requirement applicable to your investment.

Class N Shares

Class N shares of the Fund are subject to a $1,000,000 initial investment minimum. This minimum applies to Fee Based Programs and accounts (such as wrap accounts) where an advisory fee is paid to the broker-dealer or other financial intermediary. There is no subsequent investment minimum for these shares. There is no initial investment minimum for:

In its sole discretion, the Distributor may waive the investment minimum requirement for accounts as to which the Distributor reasonably believes will have enough assets to exceed the investment minimum requirement within a relatively short period of time following the establishment date of such accounts in Class N. The Distributor and the Fund, at any time, reserve the right to liquidate these accounts or any other account that does not meet the eligibility requirements of this class.

Class T Shares

Class T shares of the Fund are not currently available for purchase.

Class T shares of the Fund may only be purchased by investors who are investing through an authorized third party, such as a broker-dealer or other financial intermediary, that has entered into a selling agreement with the Distributor. Investors may not hold Class T shares directly with the Fund. Class T shares are subject to a minimum initial investment of $2,500 and a minimum subsequent investment of $50.  Not all financial intermediaries make Class T shares available to their clients.

Class Y Shares

Class Y shares of the Fund are generally subject to a minimum initial investment of $100,000 and a minimum subsequent investment of $50, except there is no minimum initial or subsequent investment for:

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Fund Summary 

At the discretion of Natixis Advisors, clients of Natixis Advisors and its affiliates may purchase Class Y shares of the Fund below the stated minimums.

Due to operational limitations at your financial intermediary, certain fee based programs, retirement plans, individual retirement accounts and accounts of registered investment advisers may be subject to the investment minimums described above.

The Fund’s shares are available for purchase and are redeemable on any business day through your investment dealer, directly from the Fund by writing to the Fund at Natixis Funds, P.O. Box 219579, Kansas City, MO 64121-9579, by exchange, by wire, by internet at im.natixis.com (certain restrictions may apply), through the Automated Clearing House system, or, in the case of redemptions, by telephone at 800-225-5478 or by the Systematic Withdrawal Plan. 

Tax Information

Fund distributions are generally taxable to you as ordinary income or capital gains, except for distributions to retirement plans and other investors that qualify for tax-advantaged treatment under U.S. federal income tax law generally. Investments in such tax-advantaged plans will generally be taxed only upon withdrawal of monies from the tax-advantaged arrangement.

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 the 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.

UIDB77-0223