Form 485BPOS ULTRA SERIES FUND

The Conservative Allocation Fund seeks income, capital appreciation and relative stability of value.

This 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 the table and example below. Actual expenses may be greater or less than those shown. The expenses do not reflect any expenses, fees or charges paid under your variable contract or retirement plan. If these expenses, fees or charges were included, your costs would be higher.

¹Fees and expenses incurred indirectly by the Fund as a result of investing in the shares of one or more underlying funds. 

²Total annual fund operating expenses for the year ended December 31, 2025 do not correlate to the ratio of expenses to average net assets provided in the financial highlights section of the prospectus, which reflects only the operating expenses of the Fund and does not include acquired fund fees and expenses.

The example does not reflect any expenses, fees or charges paid under your variable contract or retirement plan. If these expenses, fees or charges were included, your costs would be higher.

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. These costs, which are not reflected in total annual Fund operating expenses or in the expense examples above, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 28% of the average value of its portfolio.

The Fund invests primarily in shares of other registered investment companies, including those whose shares trade on a stock exchange (exchange traded funds or “ETFs”) (the “underlying funds”). The Fund will be diversified among a number of asset classes and its allocation among underlying funds will be based on an asset allocation model developed by Madison Asset Management, LLC (“Madison”), the Fund’s investment adviser. Under normal circumstances, the Fund’s total net assets will be allocated among various asset classes and underlying funds, with target allocations over time of approximately 35% equity investments (including foreign equity), and 65% fixed income investments. Underlying funds in which the Fund invests may include funds advised by Madison and/or its affiliates, including the Madison Funds and Madison ETFs Trust (the “affiliated underlying funds”). Generally, Madison will not invest more than 75% of the Fund’s net assets, at the time of purchase, in affiliated underlying funds. Although actual allocations may vary, as of December 31, 2025, the Fund’s portfolio allocation as a percentage of net assets was:

With regard to investments in debt securities, Madison’s bias is toward securities with intermediate and short-term maturities. As of December 31, 2025, the weighted average duration of the Fund’s debt portfolio was 5.59 years.

Madison may employ multiple analytical approaches to determine the appropriate asset allocation for the Fund, including: 

In addition, Madison has a flexible mandate which permits the Fund, at the sole discretion of Madison, to materially reduce equity risk exposures when and if conditions are deemed to warrant such an action.

The Fund’s investment strategy reflects Madison’s general “Participate and Protect^®” investment philosophy. Madison’s expectation is that investors in the Fund will participate in market appreciation during bull markets and experience something less than full participation during bear markets compared with investors in portfolios holding more speculative and volatile securities; therefore, this investment philosophy is intended to represent a conservative investment strategy. There is no assurance that Madison’s expectations regarding this investment strategy will be realized.

Although the Fund expects to pursue its investment objective utilizing its principal investment strategies regardless of market conditions, the Fund may invest up to 100% in cash, money market funds, and/or money market instruments. To the extent the Fund engages in this temporary defensive position, the Fund’s ability to achieve its investment objective may be diminished.

Underlying Funds Risk. The Fund is a fund of funds, meaning that it invests primarily in the shares of underlying funds, including ETFs. Thus, the Fund’s investment performance and its ability to achieve its investment goal are directly related to the performance of the underlying funds in which it invests. Each underlying fund’s performance, in turn, depends on the particular securities in which that underlying fund invests and the expenses of that underlying fund. Accordingly, the Fund is subject to the risks of the underlying funds in direct proportion to the allocation of its assets among the underlying funds.

Asset Allocation Risk. The Fund is subject to asset allocation risk, which is the risk that the selection of the underlying funds and the allocation of the Fund’s assets among the various asset classes and market segments will cause the Fund to underperform other funds with a similar investment objective.

Interest Rate Risk. The Fund, through the underlying funds, is subject to interest rate risk, which is the risk that the value of your investment will fluctuate with changes in interest rates. Typically, a rise in interest rates causes a decline in the market value of income-bearing securities. When interest rates rise, bond prices fall; generally, the longer a bond’s maturity, the more sensitive it is to this risk.

Credit and Prepayment/Extension Risk. The Fund, through the underlying funds, is also subject to credit risk, which is the risk that issuers of debt securities may be unable to meet their interest or principal payment obligations when due. There is also prepayment/extension risk, which is the chance that a rise/fall in interest rates will reduce/extend the life of a mortgage-backed security by increasing/decreasing mortgage prepayments, typically reducing the underlying fund’s return.

Non-Investment Grade Security Risk. The Fund, through the underlying funds, may invest in non-investment grade securities (i.e., “junk” bonds). Issuers of non-investment grade securities are typically in weak financial health and their ability to pay interest and principal is uncertain. Compared to issuers of investment-grade bonds, they are more likely to encounter financial difficulties and to be materially affected by these difficulties when they do encounter them. “Junk” bond markets may react strongly to adverse news about an issuer or the economy, or to the perception or expectation of adverse news.

Equity Risk. The Fund, through the underlying funds, is subject to equity risk. Equity risk is the risk that securities held by the Fund will fluctuate in value due to general market or economic conditions, perceptions regarding the industries in which the issuers of securities held by the Fund participate, and the circumstances and performance of companies whose securities the Fund holds. In addition, while broad market measures of common stocks have historically generated higher average returns than fixed income securities, common stocks have also experienced significantly more volatility in those returns.

ETF Risks. The main risks of investing in ETFs are the same as investing in a portfolio of equity securities comprising the index on which the ETF is based, although lack of liquidity in an ETF could result in it being more volatile than the securities comprising the index. Additionally, the market prices of ETFs will fluctuate in accordance with both changes in the market value of their underlying portfolio securities and due to supply and demand for the instruments on the exchanges on which they are traded (which may result in their trading at a discount or premium to their net asset values). Index-based ETF investments may not replicate exactly the performance of their specific index because of transaction costs and because of the temporary unavailability of certain component securities of the index.

Foreign Security Risk. Investments of underlying funds that invest in foreign securities involve risks relating to currency fluctuations and to political, social and economic developments abroad, as well as risks resulting from differences between the regulations to which U.S. and foreign issuers and markets are subject. The investment markets of emerging countries are generally more volatile than markets of developed countries with more mature economies.

Market Risk. While the majority of the Fund’s assets will typically be invested in underlying funds that invest primarily in debt securities, to the extent that the Fund invests in underlying funds that invest in equities, the Fund is subject to market risk, which is the risk that the value of an investment may fluctuate in response to stock market movements.

The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows how the Fund’s investment results have varied from year to year. The table shows the Fund’s average annual total returns for one, five and ten year periods compared to a broad market index, as well as a custom index that reflects the Fund’s asset allocation targets. Neither the bar chart nor the table reflects charges deducted in connection with variable contracts. If these charges were reflected, returns would be less than those shown. The Fund’s past performance is not necessarily an indication of its future performance. Updated performance information current to the most recent month-end is available at no cost by visiting www.ultraseriesfund.com or by calling 1-800-670-3600.

Madison waived 0.10% of the 0.30% annualized management fee for the period July 1, 2014 through April 30, 2022. If the management fee had not been waived, returns would have been lower.

Average Annual Total Returns¹ 

For Periods Ended December 31, 2025 

¹ Fund returns are calculated after fund expenses have been subtracted and assume that dividends and capital gains are reinvested in additional shares of a fund. Returns do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares. Investment return and principal value will fluctuate, so an investor’s shares, when redeemed, may be worth more or less than original cost. Further information relating to the fund’s performance is contained in the prospectus and at www.madisonfunds.com/funds/ultra-series-fund. The Fund’s past performance is not indicative of future performance. 

² The ICE BofA U.S. Corporate, Government & Mortgage Index is a broad-based measure of the total rate of return performance of the U.S. investment-grade bond markets. The index is a capitalization-weighted aggregation of outstanding U.S. treasury, agency and supranational mortgage pass-through, and investment-grade corporate bonds meeting specified selection criteria. 

³ The Bloomberg US Aggregate Bond Index is a broad-based flagship benchmark that measures the investment grade, US dollar-denominated, fixed-rate taxable bond market. 

⁴ The Conservative Allocation Fund Custom Index consists of 65% Bloomberg U.S. Aggregate Bond Index, 24.5% Russell 3000^® Index, and 10.5% MSCI ACWI ex-USA Index (net).

 The Conservative Allocation Fund Custom Index consists of 65% Bloomberg U.S. Aggregate Bond Index, 24.5% Russell 3000® Index, and 10.5% MSCI ACWI ex-USA Index (net).

The Moderate Allocation Fund seeks capital appreciation, income and moderate market risk.

This 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 the table and example below. Actual expenses may be greater or less than those shown. The expenses do not reflect any expenses, fees or charges paid under your variable contract or retirement plan. If these expenses, fees or charges were included, your costs would be higher.

¹Fees and expenses incurred indirectly by the Fund as a result of investing in the shares of one or more underlying funds. 

²Total annual fund operating expenses for the year ended December 31, 2025 do not correlate to the ratio of expenses to average net assets provided in the financial highlights section of the prospectus, which reflects only the operating expenses of the Fund and does not include acquired fund fees and expenses.

The example does not reflect any expenses, fees or charges paid under your variable contract or retirement plan. If these expenses, fees or charges were included, your costs would be higher.

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. These costs, which are not reflected in total annual Fund operating expenses or in the expense examples above, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 32% of the average value of its portfolio.

The Fund invests primarily in shares of other registered investment companies, including those whose shares trade on a stock exchange (exchange traded funds or “ETFs”) (the “underlying funds”). The Fund will be diversified among a number of asset classes and its allocation among underlying funds will be based on an asset allocation model developed by Madison Asset Management, LLC (“Madison”), the Fund’s investment adviser. Under normal circumstances, the Fund’s total net assets will be allocated among various asset classes and underlying funds, with target allocations over time of approximately 60% equity investments (including foreign equity) and 40% fixed income investments. Underlying funds in which the Fund invests may include funds advised by Madison and/or its affiliates, including the Madison Funds and Madison ETFs Trust (the “affiliated underlying funds”). Generally, Madison will not invest more than 75% of the Fund’s net assets, at the time of purchase, in affiliated underlying funds. Although actual allocations may vary, as of December 31, 2025, the Fund’s portfolio allocation as a percentage of net assets was:

With regard to investments in debt securities, Madison’s bias is toward securities with intermediate and short-term maturities. As of December 31, 2025, the weighted average duration of the Fund’s debt portfolio was 5.63 years.

Madison may employ multiple analytical approaches to determine the appropriate asset allocation for the Fund, including: 

In addition, Madison has a flexible mandate which permits the Fund, at the sole discretion of Madison, to materially reduce equity risk exposures when and if conditions are deemed to warrant such an action.

The Fund’s investment strategy reflects Madison’s general “Participate and Protect^®” investment philosophy.  Madison’s expectation is that investors in the Fund will participate in market appreciation during bull markets and experience something less than full participation during bear markets compared with investors in portfolios holding more speculative and volatile securities; therefore, this investment philosophy is intended to represent a conservative investment strategy. There is no assurance that Madison’s expectations regarding this investment strategy will be realized.

Although the Fund expects to pursue its investment objective utilizing its principal investment strategies regardless of market conditions, the Fund may invest up to 100% in cash, money market funds, and/or money market instruments. To the extent the Fund engages in this temporary defensive position, the Fund’s ability to achieve its investment objective may be diminished.

Underlying Funds Risk. The Fund is a fund of funds, meaning that it invests primarily in the shares of underlying funds, including ETFs. Thus, the Fund’s investment performance and its ability to achieve its investment goal are directly related to the performance of the underlying funds in which it invests. Each underlying fund’s performance, in turn, depends on the particular securities in which that underlying fund invests and the expenses of that underlying fund. Accordingly, the Fund is subject to the risks of the underlying funds in direct proportion to the allocation of its assets among the underlying funds.

Asset Allocation Risk. The Fund is subject to asset allocation risk, which is the risk that the selection of the underlying funds and the allocation of the Fund’s assets among the various asset classes and market segments will cause the Fund to underperform other funds with a similar investment objective.

Equity Risk. The Fund, through the underlying funds, is subject to equity risk. Equity risk is the risk that securities held by the Fund will fluctuate in value due to general market or economic conditions, perceptions regarding the industries in which the issuers of securities held by the Fund participate, and the circumstances and performance of companies whose securities the Fund holds. In addition, while broad market measures of common stocks have historically generated higher average returns than fixed income securities, common stocks have also experienced significantly more volatility in those returns.

Interest Rate Risk. The Fund, through the underlying funds, is subject to interest rate risk, which is the risk that the value of your investment will fluctuate with changes in interest rates. Typically, a rise in interest rates causes a decline in the market value of income-bearing securities. When interest rates rise, bond prices fall; generally, the longer a bond’s maturity, the more sensitive it is to this risk.

Credit and Prepayment/Extension Risk. The Fund, through the underlying funds, is also subject to credit risk, which is the risk that issuers of debt securities may be unable to meet their interest or principal payment obligations when due. There is also prepayment/extension risk, which is the chance that a rise/fall in interest rates will reduce/extend the life of a mortgage-backed security by increasing/decreasing mortgage prepayments, typically reducing the underlying fund’s return.

Non-Investment Grade Security Risk. The Fund, through the underlying funds, may invest in non-investment grade securities (i.e., “junk” bonds). Issuers of non-investment grade securities are typically in weak financial health and their ability to pay interest and principal is uncertain. Compared to issuers of investment grade bonds, they are more likely to encounter financial difficulties and to be materially affected by these difficulties when they do encounter them. “Junk” bond markets may react strongly to adverse news about an issuer or the economy, or to the perception or expectation of adverse news.

ETF Risks. The main risks of investing in ETFs are the same as investing in a portfolio of equity securities comprising the index on which the ETF is based, although lack of liquidity in an ETF could result in it being more volatile than the securities comprising the index. Additionally, the market prices of ETFs will fluctuate in accordance with both changes in the market value of their underlying portfolio securities and due to supply and demand for the instruments on the exchanges on which they are traded (which may result in their trading at a discount or premium to their net asset values). Index-based ETF investments may not replicate exactly the performance of their specific index because of transaction costs and because of the temporary unavailability of certain component securities of the index.

Foreign Security Risk. Investments in foreign securities involve risks relating to currency fluctuations and to political, social and economic developments abroad, as well as risks resulting from differences between the regulations to which U.S. and foreign issuers and markets are subject. The investment markets of emerging countries are generally more volatile than markets of developed countries with more mature economies.

Market Risk. The Fund, through the underlying funds, is subject to market risk, which is the risk that the value of an investment may fluctuate in response to stock market movements. Certain of the underlying funds may invest in the equity securities of smaller companies, which may fluctuate more in value and be more thinly traded than the general market.

The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows how the Fund’s investment results have varied from year to year. The table shows the Fund’s average annual total returns for one, five and ten year periods compared to a broad market index, as well as a custom index that reflects the Fund’s asset allocation targets. Neither the bar chart nor the table reflects charges deducted in connection with variable contracts. If these charges were reflected, returns would be less than those shown. The Fund’s past performance is not necessarily an indication of its future performance. Updated performance information current to the most recent month-end is available at no cost by visiting www.ultraseriesfund.com or by calling 1-800-670-3600.

Madison waived 0.10% of the 0.30% annualized management fee for the period July 1, 2014 through April 30, 2022. If the management fee had not been waived, returns would have been lower.

Average Annual Total Returns 

For Periods Ended December 31, 2025 

¹The Moderate Allocation Fund Custom Index consists of 42% Russell 3000^® Index, 40% Bloomberg U.S. Aggregate Bond Index and 18% MSCI ACWI ex-USA Index (net).

The Aggressive Allocation Fund seeks capital appreciation.

This 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 the table and example below. Actual expenses may be greater or less than those shown. The expenses do not reflect any expenses, fees or charges paid under your variable contract or retirement plan. If these expenses, fees or charges were included, your costs would be higher.

The example does not reflect any expenses, fees or charges paid under your variable contract or retirement plan. If these expenses, fees or charges were included, your costs would be higher.

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. These costs, which are not reflected in total annual Fund operating expenses or in the expense examples above, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 34% of the average value of its portfolio.

The Fund invests primarily in shares of other registered investment companies, including those whose shares trade on a stock exchange (exchange traded funds or “ETFs”) (the “underlying funds”). The Fund will be diversified among a number of asset classes and its allocation among underlying funds will be based on an asset allocation model developed by Madison Asset Management, LLC (“Madison”), the Fund’s investment adviser. Under normal circumstances, the Fund’s total net assets will be allocated among various asset classes and underlying funds, with target allocations over time of approximately 80% equity investments (including foreign equity) and 20% fixed income investments. Underlying funds in which the Fund invests may include funds advised by Madison and/or its affiliates, including the Madison Funds and Madison ETFs Trust (the “affiliated underlying funds”). Generally, Madison will not invest more than 75% of the Fund’s net assets, at the time of purchase, in affiliated underlying funds. Although actual allocations may vary, as of December 31, 2025, the Fund’s portfolio allocation as a percentage of net assets was:

With regard to investments in debt securities, Madison’s bias is toward securities with intermediate and short-term maturities. As of December 31, 2025, the weighted average duration of the Fund’s debt portfolio was 5.61 years.

Madison may employ multiple analytical approaches to determine the appropriate asset allocation for the Fund, including: 

In addition, Madison has a flexible mandate which permits the Fund, at the sole discretion of Madison, to materially reduce equity risk exposures when and if conditions are deemed to warrant such an action.

The Fund’s investment strategy reflects Madison’s general “Participate and Protect^®” investment philosophy. Madison’s expectation is that investors in the Fund will participate in market appreciation during bull markets and experience something less than full participation during bear markets compared with investors in portfolios holding more speculative and volatile securities; therefore, this investment philosophy is intended to represent a conservative investment strategy. There is no assurance that Madison’s expectations regarding this investment strategy will be realized.

Although the Fund expects to pursue its investment objective utilizing its principal investment strategies regardless of market conditions, the Fund may invest up to 100% in cash, money market funds, and/or money market instruments. To the extent the Fund engages in this temporary defensive position, the Fund’s ability to achieve its investment objective may be diminished.

Underlying Funds Risk. The Fund is a fund of funds, meaning that it invests primarily in the shares of underlying funds, including ETFs. Thus, the Fund’s investment performance and its ability to achieve its investment goal are directly related to the performance of the underlying funds in which it invests. Each underlying fund’s performance, in turn, depends on the particular securities in which that underlying fund invests and the expenses of that underlying fund. Accordingly, the Fund is subject to the risks of the underlying funds in direct proportion to the allocation of its assets among the underlying funds.

Asset Allocation Risk. The Fund is subject to asset allocation risk, which is the risk that the selection of the underlying funds and the allocation of the Fund’s assets among the various asset classes and market segments will cause the Fund to underperform other funds with a similar investment objective.

Equity Risk. The Fund, through the underlying funds, is subject to equity risk. Equity risk is the risk that securities held by the Fund will fluctuate in value due to general market or economic conditions, perceptions regarding the industries in which the issuers of securities held by the Fund participate, and the circumstances and performance of companies whose securities the Fund holds. In addition, while broad market measures of common stocks have historically generated higher average returns than fixed income securities, common stocks have also experienced significantly more volatility in those returns.

Interest Rate Risk. To the extent that the Fund invests in underlying funds that invest in debt securities, the Fund will be subject to interest rate risk, which is the risk that the value of your investment will fluctuate with changes in interest rates. Typically, a rise in interest rates causes a decline in the market value of income-bearing securities. When interest rates rise, bond prices fall; generally, the longer a bond’s maturity, the more sensitive it is to this risk.

Credit and Prepayment/Extension Risk. The Fund, through the underlying funds, is also subject to credit risk, which is the risk that issuers of debt securities may be unable to meet their interest or principal payment obligations when due. There is also prepayment/extension risk, which is the chance that a rise/fall in interest rates will reduce/extend the life of a mortgage-backed security by increasing/decreasing mortgage prepayments, typically reducing the underlying fund’s return.

Non-Investment Grade Security Risk. The Fund, through the underlying funds, may invest in non-investment grade securities (i.e., “junk” bonds). Issuers of non-investment grade securities are typically in weak financial health and their ability to pay interest and principal is uncertain. Compared to issuers of investment grade bonds, they are more likely to encounter financial difficulties and to be materially affected by these difficulties when they do encounter them. “Junk” bond markets may react strongly to adverse news about an issuer or the economy, or to the perception or expectation of adverse news.

ETF Risks. The main risks of investing in ETFs are the same as investing in a portfolio of equity securities comprising the index on which the ETF is based, although lack of liquidity in an ETF could result in it being more volatile than the securities comprising the index. Additionally, the market prices of ETFs will fluctuate in accordance with both changes in the market value of their underlying portfolio securities and due to supply and demand for the instruments on the exchanges on which they are traded (which may result in their trading at a discount or premium to their net asset values). Index-based ETF investments may not replicate exactly the performance of their specific index because of transaction costs and because of the temporary unavailability of certain component securities of the index.

Foreign Security Risk. Investments in foreign securities involve risks relating to currency fluctuations and to political, social and economic developments abroad, as well as risks resulting from differences between the regulations to which U.S. and foreign issuers and markets are subject. The investment markets of emerging countries are generally more volatile than markets of developed countries with more mature economies.

Market Risk. The Fund, through the underlying funds, is subject to market risk, which is the risk that the value of an investment may fluctuate in response to stock market movements. Certain of the underlying funds may invest in the equity securities of smaller companies, which may fluctuate more in value and be more thinly traded than the general market.

The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows how the Fund’s investment results have varied from year to year. The table shows the Fund’s average annual total returns for one, five and ten year periods compared to a broad market index, as well as a custom index that reflects the Fund’s asset allocation targets. Neither the bar chart nor the table reflects charges deducted in connection with variable contracts. If these charges were reflected, returns would be less than those shown. The Fund’s past performance is not necessarily an indication of its future performance. Updated performance information current to the most recent month-end is available at no cost by visiting www.ultraseriesfund.com or by calling 1-800-670-3600.

Madison waived 0.10% of the 0.30% annualized management fee for the period July 1, 2014 through April 30, 2022. If the management fee had not been waived, returns would have been lower.

Average Annual Total Returns 

For Periods Ended December 31, 2025 

The Diversified Income Fund seeks a high total return through the combination of income and capital appreciation.

This 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 the table and example below. Actual expenses may be greater or less than those shown. The expenses do not reflect any expenses, fees or charges paid under your variable contract or retirement plan. If these expenses, fees or charges were included, your costs would be higher.

The example does not reflect any expenses, fees or charges paid under your variable contract or retirement plan. If these expenses, fees or charges were included, your costs would be higher.

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. These costs, which are not reflected in total annual Fund operating expenses or in the expense examples above, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 20% of the average value of its portfolio.

The Fund invests primarily in shares of other registered investment companies, including those whose shares trade on a stock exchange (exchange traded funds or “ETFs”) (the “underlying funds”). The Fund will be diversified among several asset classes and its allocation among underlying funds will be based on an asset allocation model developed by Madison Asset Management (“Madison”), the Fund’s investment adviser. Under normal circumstances, the Fund’s total net assets will be allocated among various asset classes and underlying funds, with target allocations over time of approximately 50% equity investments and 50% fixed income investments. Underlying funds in which the Fund invests may include funds advised by Madison and/or its affiliates, including other Madison Funds and ETFs (the “affiliated underlying funds”). Generally, Madison will not invest more than 80% of the Fund’s net assets, at the time of purchase, in affiliated underlying funds. Although actual allocations may vary, as of December 31, 2025, the Fund’s portfolio allocation as a percentage of net assets was:

With regard to investments in debt securities, Madison’s bias is toward securities with intermediate and short-term maturities. As of December 31, 2025, the weighted average duration of the Fund’s debt portfolio was 3.89 years.

Madison may employ multiple analytical approaches to determine the appropriate allocation among the underlying funds, including: 

In addition, Madison has a flexible mandate that permits the Fund, at the sole discretion of Madison, to materially reduce equity risk exposures when and if conditions are deemed to warrant such an action.

The Fund’s investment strategy reflects Madison’s general “Participate and Protect®” investment philosophy. Madison’s expectation is that investors in the Fund will participate in market appreciation during bull markets and experience something less than full participation during bear markets compared with investors in portfolios holding more speculative and volatile securities; therefore, this investment philosophy is intended to represent a conservative investment strategy. There is no assurance that Madison’s expectations regarding this investment strategy will be realized.

Although the Fund expects to pursue its investment objective utilizing its principal investment strategies regardless of market conditions, the Fund may invest up to 100% in cash, money market funds, and/or money market instruments. To the extent the Fund engages in this temporary defensive position, the Fund’s ability to achieve its investment objective may be diminished.

Underlying Funds Risk. The Fund is a fund of funds, meaning that it invests primarily in the shares of underlying funds, including ETFs. Thus, the Fund’s investment performance and its ability to achieve its investment goal are directly related to the performance of the underlying funds in which it invests. Each underlying fund’s performance, in turn, depends on the particular securities in which that underlying fund invests and the expenses of that underlying fund. Accordingly, the Fund is subject to the risks of the underlying funds in direct proportion to the allocation of its assets among the underlying funds.

Asset Allocation Risk. The Fund is subject to asset allocation risk, which is the risk that the selection of the underlying funds and the allocation of the Fund’s assets among the various asset classes and market segments will cause the Fund to underperform other funds with a similar investment objective.

ETF Risks. The main risks of investing in ETFs are the same as investing in a portfolio of equity securities comprising the index on which the ETF is based, although lack of liquidity in an ETF could result in it being more volatile than the securities comprising the index. Additionally, the market prices of ETFs will fluctuate in accordance with both changes in the market value of their underlying portfolio securities and due to supply and demand for the instruments on the exchanges on which they are traded (which may result in their trading at a discount or premium to their net asset values). Index-based ETF investments may not replicate exactly the performance of their specific index because of transactions costs and because of the temporary unavailability of certain component securities of the index.

Equity Risk. The Fund is subject to equity risk. Equity risk is the risk that securities held by the Fund will fluctuate in value due to general market or economic conditions, perceptions regarding the industries in which the issuers of securities held by the Fund participate, and the circumstances and performance of companies whose securities the Fund holds. In addition, while broad market measures of common stocks have historically generated higher average returns than fixed income securities, common stocks have also experienced significantly more volatility in those returns.

Interest Rate Risk. The Fund is subject to interest rate risk, which is the risk that the value of your investment will fluctuate with changes in interest rates. Typically, a rise in interest rates causes a decline in the market value of income-bearing securities. When interest rates rise, bond prices fall; generally, the longer a bond’s maturity, the more sensitive it is to this risk.

Credit Risk. The Fund is subject to credit risk, which is the risk that issuers of debt securities may be unable to meet their interest or principal payment obligations when due.

Non-Investment Grade Security Risk. Issuers of non-investment grade securities (i.e., “junk” bonds) are typically in weak financial health and, compared to issuers of investment-grade bonds, they are more likely to encounter financial difficulties and to be materially affected by these difficulties when they do encounter them. Because the Fund may invest a significant portion of its assets in these securities, the Fund may be subject to greater levels of credit and liquidity risk than a Fund that does not invest in such securities. These securities are considered predominately speculative with respect to the issuer’s continuing ability to make principal and interest payments. 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 these securities. If the issuer of a security is in default with respect to interest or principal payments, the Fund may lose its entire investment. Because of the risks involved in investing in non-investment grade securities, an investment in a Fund that invests in such securities should be considered speculative.

Real Estate Investment Trusts (“REITs”) Risk. REITs pool investors’ funds for investment primarily in real estate properties or real estate-related loans. REITs generally derive their income from rents on the underlying properties or interest on the underlying loans, and their value is impacted by changes in the value of the underlying property or changes in interest rates affecting the underlying loans owned by the REITs. REITs are more susceptible to risks associated with the ownership of real estate and the real estate industry in general. These risks can include, but are not limited, fluctuations in the value of underlying properties; defaults by borrowers or tenants; market saturation; changes in general and local economic conditions; decreases in market rates for rents; increases in competition, property taxes, capital expenditures or operating expenses; and other economic, political or regulatory occurrences affecting the real estate industry. In addition, REITs depend upon specialized management skills, may not be diversified (which may increase the price volatility of REITs), may have less trading volume and liquidity, and may be subject to more abrupt or erratic price movements than the overall securities market. REITs are not taxed on income distributed to shareholders provided they comply with several requirements of the Internal Revenue Code of 1986, as amended. REITs are subject to the risk of failing to qualify for favorable tax treatment under the Code.

Foreign Security and Emerging Market Risk. Investments in foreign securities, including investments in ADRs and emerging market securities, involve risks relating to currency fluctuations and to political, social and economic developments abroad, as well as risks resulting from differences between the regulations to which U.S. and foreign issuers and markets are subject. These risks may be greater in emerging markets. The investment markets of emerging countries are generally more volatile than markets of developed countries with more mature economies.

Depository Receipt Risk. Depository receipts, such as ADRs, and global depository receipts (“GDRs”), may be issued in sponsored or un-sponsored programs. In a sponsored program, a security issuer has made arrangements to have its securities traded in the form of depository receipts. In an un-sponsored program, the issuer may not be directly involved in the creation of the program. Depository receipts involve many of the same risks as direct investments in foreign securities. These risks include, but are not limited to: fluctuations in currency exchange rates, which are affected by international balances of payments and other financial conditions; government interventions; and speculation. With respect to certain foreign countries, there is the possibility of expropriation or nationalization of assets, confiscatory taxation, political and social upheaval, and economic instability. Investments in depository receipts that are traded over the counter may also be subject to liquidity risk.

Market Risk. The share price of the Fund reflects the value of the securities it holds. If a security’s price falls, the share price of the Fund will go down (unless another security’s price rises by an offsetting amount). If the Fund’s share price falls below the price you paid for your shares, you could lose money when you redeem your shares.

The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows how the Fund’s investment results have varied from year to year. The table shows the Fund’s average annual total returns for one, five and ten year periods compared to broad measures of market performance, as well as a custom index that reflects a hypothetical investment allocation of 50% bonds and 50% stocks. Neither the bar chart nor the table reflects charges deducted in connection with variable contracts. If these charges were reflected, returns would be less than those shown. The Fund’s past performance is not necessarily an indication of its future performance. Performance data presented below for all periods prior to July 31, 2023, represents the performance of the previous portfolio management team of Madison who used different principal investment strategies to achieve the Fund’s investment objective. Updated performance information current to the most recent month-end is available at no cost by visiting www.ultraseriesfund.com or by calling 1-800-670-3600.

Average Annual Total Returns¹ 

For Periods Ended December 31, 2025 

The Core Bond Fund seeks to generate a high level of current income, consistent with the prudent limitation of investment risk.

This 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 the table and example below. Actual expenses may be greater or less than those shown. The expenses do not reflect any expenses, fees or charges paid under your variable contract or retirement plan. If these expenses, fees or charges were included, your costs would be higher.

The example does not reflect any expenses, fees or charges paid under your variable contract or retirement plan. If these expenses, fees or charges were included, your costs would be higher.

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. These costs, which are not reflected in total annual Fund operating expenses or in the expense examples above, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 13% of the average value of its portfolio.

Under normal market conditions, the Fund invests at least 80% of its net assets (including borrowings for investment purposes) in bonds. To keep current income relatively stable and to limit share price volatility, the Fund emphasizes investment grade securities and maintains an intermediate (typically 3-7 year) average portfolio duration, with the goal of being between 85-115% of the market benchmark duration (for this purpose, the benchmark used is the Bloomberg U.S. Aggregate Bond Index, the duration of which as of December 31, 2025 was 5.81 years). Duration is an approximation of the expected change in a debt security’s price given a 1% move in interest rates, using the following formula: [change in debt security value = (change in interest rates) x (duration) x (-1)]. By way of example, assume XYZ company issues a five year bond which has a duration of 4.5 years. If interest rates were to instantly increase by 1%, the bond would be expected to decrease in value by approximately 4.5%.

The Fund is managed so that, under normal market conditions, the weighted average life of the Fund will be 10 years or less. The weighted average life of the Fund as of December 31, 2025 was 8.24 years. The Fund strives to add incremental return in the portfolio by making strategic decisions relating to credit risk, sector exposure and yield curve positioning. The Fund generally holds 100-500 individual securities in its portfolio at any given time and may invest in the following instruments:

Madison may alter the composition of the Fund with regard to quality and maturity and may sell securities prior to maturity. Under normal market conditions, however, turnover for the Fund is generally not expected to exceed 100%. Sales of Fund securities may result in capital gains. This can occur any time Madison sells a bond at a price that was higher than the purchase price, even if Madison does not engage in active or frequent trading. Madison’s intent when it sells bonds is to “lock in” any gains already achieved by that investment or, alternatively, prevent additional or potential losses that could occur if Madison continued to hold the bond. Turnover may also occur when Madison finds an investment that could generate a higher return than the investment currently held. However, increasing portfolio turnover at a time when Madison’s assessment of market performance is incorrect could lower investment performance. The Fund pays implied brokerage commissions when it purchases or sells bonds, which is the difference between the bid and ask price. As a result, as portfolio turnover increases, the cumulative effect of this may hurt Fund performance. Under normal market conditions, the Fund will not engage in active or frequent trading of its bonds. However, it is possible that Madison will determine that market conditions require a significant change to the composition of the Fund’s portfolio. For example, if interest rates begin to rise, Madison may attempt to sell bonds in anticipation of further rate increases before they lose more value. Also, if the Fund experiences large swings in shareholder purchases and redemptions, Madison may be required to sell bonds more frequently in order to generate the cash needed to pay redeeming shareholders.

Madison reserves the right to invest a portion of the Fund’s assets in short-term debt securities (i.e., those with maturities of one year or less) and to maintain a portion of Fund assets in uninvested cash. However, Madison does not intend to hold more than 35% of the Fund’s assets in such investments, unless Madison determines that market conditions warrant a temporary defensive investment position. Under such circumstances, the Fund may invest up to 100% in cash, money market funds, and/or tax-free money market instruments. To the extent the Fund engages in this temporary defensive position, the Fund’s ability to achieve its investment objective may be diminished. Short-term investments may include investment grade certificates of deposit, commercial paper and repurchase agreements. Madison might hold substantial cash reserves in seeking to reduce the Fund’s exposure to bond price depreciation during a period of rising interest rates and to maintain desired liquidity while awaiting more attractive investment conditions in the bond market.

The Fund’s investment strategy reflects Madison’s general “Participate and Protect^®” investment philosophy. Madison’s expectation is that investors in the Fund will participate in market appreciation during bull markets and experience something less than full participation during bear markets compared with investors in portfolios holding more speculative and volatile securities; therefore, this investment philosophy is intended to represent a conservative investment strategy. There is no assurance that Madison’s expectations regarding this investment strategy will be realized.

Interest Rate Risk. As with most income funds, the Fund is subject to interest rate risk, which is the risk that the value of your investment will fluctuate with changes in interest rates. Typically, a rise in interest rates causes a decline in the market value of income bearing securities. When interest rates rise, bond prices fall; generally, the longer the bond’s maturity, the more sensitive it is to this risk.

Call Risk. If a bond issuer “calls” a bond held by the Fund (i.e., pays it off at a specified price before it matures), the Fund could have to reinvest the proceeds at a lower interest rate. It may also experience a loss if the bond is called at a price lower than what the Fund paid for the bond.

Risk of Default. Although Madison monitors the condition of bond issuers, it is still possible that unexpected events could cause the issuer to be unable to pay either principal or interest on its bond. This could cause the bond to go into default and lose value. Some federal agency securities are not backed by the full faith and credit of the United States, so in the event of default, the Fund would have to look to the agency issuing the bond for ultimate repayment.

Mortgage-Backed Securities Risk. The Fund may own obligations backed by mortgages issued by a government agency or through a government-sponsored program. If the mortgage holders prepay principal during a period of falling interest rates, the Fund could be exposed to prepayment risk. In that case, the Fund would have to reinvest the proceeds at a lower interest rate. The security itself may not increase in value with the corresponding drop in rates since the prepayment acts to shorten the maturity of the security.

Liquidity Risk. The Fund is also subject to liquidity risk, which means there may be little or no trading activity for the debt securities in which the Fund invests, and that may make it difficult for the Fund to value accurately and/or sell those securities. In addition, liquid debt securities in which the Fund invests are subject to the risk that during certain periods their liquidity will shrink or disappear suddenly and without warning as a result of adverse economic, regulatory or market conditions, or adverse investor perceptions. If the Fund experiences rapid, large redemptions during a period in which a substantial portion of its debt securities are illiquid, the Fund may be forced to sell those securities at a discount, which could result in significant Fund and shareholder losses.

Credit Risk and Prepayment/Extension Risk. The Fund is subject to credit risk, which is the risk that issuers of debt securities may be unable to meet their interest or principal payment obligations when due. There is also prepayment/extension risk, which is the chance that a fall/rise in interest rates will reduce/extend the life of a mortgage-backed security by increasing/decreasing mortgage prepayments, typically reducing the Fund’s return.

Non-Investment Grade Security Risk. To the extent that the Fund invests in non-investment grade securities, the Fund is also subject to above-average credit, market and other risks. Issuers of non-investment grade securities (i.e., “junk” bonds) are typically in weak financial health and their ability to pay interest and principal is uncertain. Compared to issuers of investment grade bonds, they are more likely to encounter financial difficulties and to be materially affected by these difficulties when they do encounter them. “Junk” bond markets may react strongly to adverse news about an issuer or the economy, or to the perception or expectation of adverse news.

Foreign Security Risk. Investments in foreign securities involve risks relating to currency fluctuations and to political, social and economic developments abroad, as well as risks resulting from differences between the regulations to which U.S. and foreign issuers and markets are subject. The investment markets of emerging countries are generally more volatile than markets of developed countries with more mature economies.

The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows how the Fund’s investment results have varied from year to year. The table shows the Fund’s average annual total returns for one, five and ten year periods compared to a broad measure of market performance. Neither the bar chart nor the table reflects charges deducted in connection with variable contracts. If these charges were reflected, returns would be less than those shown. The Fund’s past performance is not necessarily an indication of its future performance. Updated performance information current to the most recent month-end is available at no cost by visiting www.ultraseriesfund.com or by calling 1-800-670-3600.

Average Annual Total Returns  

For Periods Ended December 31, 2025