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Fees and Expenses This table describes the fees and expenses that you may pay when you hold shares of the fund. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which the fund is offered were included, your expenses would be higher. Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): 0.0090 0.0090 0 0.0025 0.0026 0.0026 0.0116 0.0141 -0.0028 -0.0028 0.0088 0.0113 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. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, your expenses would be higher.The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods; your investment has a 5% return each year; and the fund’s operating expenses remain the same. Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 90 341 611 1384 115 419 744 1667 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. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 44% of the average value of its portfolio. 0.44 Principal Investment Strategies MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests the fund’s assets primarily in equity securities. Equity securities include common stocks, depositary receipts, equity interests in real estate investment trusts (REITs), and other securities that represent an ownership interest (or right to acquire an ownership interest) in a company or other issuer.MFS focuses on investing the fund's assets in the stocks of companies it believes are undervalued compared to their perceived worth (value companies). While MFS may invest the fund’s assets in securities of companies of any size, MFS primarily invests in securities of companies with small capitalizations.MFS may invest the fund’s assets in foreign securities. MFS normally invests the fund's assets across different industries and sectors, but MFS may invest a significant percentage of the fund's assets in issuers in a single industry or sector.MFS uses an active bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual issuers. Quantitative screening tools that systematically evaluate issuers may also be considered. Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.The principal risks of investing in the fund are: Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Investment Selection Risk: MFS' investment analysis and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. In addition, to the extent MFS considers quantitative tools in managing the fund, such tools may not produce the intended results. Equity Market Risk/Company Risk: Equity markets are volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the equity markets in general. Certain events can have a dramatic adverse effect on equity markets and may lead to periods of high volatility in an equity market or a segment of an equity market. The value of an investment held by the fund may decline due to factors directly related to the issuer. Value Company Risk: The stocks of value companies can continue to be undervalued for long periods of time and not realize their expected value and can be more volatile than the market in general. Small Cap Risk: The stocks of small cap companies can be more volatile and their shares can be less liquid than those of larger companies. Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to countries with developing economies or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market. REITs Risk: The risks of investing in REITs include certain risks associated with the direct ownership of real estate and the real estate industry in general. These include risks related to general, regional and local economic conditions; difficulties in valuing and disposing of real estate; fluctuations in interest rates and property tax rates; shifts in zoning laws, environmental regulations and other governmental action; cash flow dependency; increased operating expenses; lack of availability of mortgage funds; losses due to natural disasters; overbuilding; losses due to casualty or condemnation; changes in property values and rental rates; the management skill and creditworthiness of the REIT manager; and other factors. The securities of smaller real estate-related issuers can be more volatile and less liquid than securities of larger issuers and their issuers can have more limited financial resources. Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries, and regions to which the fund is exposed. Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs. Large Shareholder Risk: From time to time, shareholders of the fund (which may include institutional investors, financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund shares. These transactions may cause the fund to sell securities or invest additional cash, as the case may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance to the extent that it takes time to invest new cash and the fund maintains a larger cash position than it ordinarily would. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests.The fund’s past performance does not necessarily indicate how the fund will perform in the future. Updated performance is available at mfs.com or by calling 1-877-411-3325. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, they would reduce the returns shown. The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests. The fund’s past performance does not necessarily indicate how the fund will perform in the future. mfs.com 1-877-411-3325 Initial Class Bar Chart. The total return for the three-month period ended March 31, 2025, was (5.38)%. During the period(s) shown in the bar chart, the highest quarterly return was 31.09% (for the calendar quarter ended December 31, 2020) and the lowest quarterly return was (34.08)% (for the calendar quarter ended March 31, 2020). The total return for the three-month period ended 2025-03-31 highest quarterly return 0.3109 2020-12-31 lowest quarterly return -0.3408 2020-03-31 Performance Table. Average Annual Total Returns (For the Periods Ended December 31, 2024) 0.0952 0.0871 0.0995 0.0918 0.0840 0.0967 Reflects no deduction for fees, expenses, or taxes Reflects no deduction for fees, expenses, or taxes Russell 3000® Index 0.2381 0.1386 0.1255 Russell 2000® Value Index 0.0805 0.0729 0.0714 MFS® Conservative Allocation Portfolio Summary of Key Information N/A N/A Investment Objective The fund's investment objective is to seek a high level of total return consistent with a conservative level of risk relative to the other MFS Asset Allocation Portfolios. (The MFS Asset Allocation Portfolios currently are MFS Conservative Allocation Portfolio, MFS Moderate Allocation Portfolio, and MFS Growth Allocation Portfolio.) Fees and Expenses This table describes the fees and expenses that you may pay when you hold shares of the fund. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which the fund is offered were included, your expenses would be higher. Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): 0.0000 0.0000 0 0.0025 0.0005 0.0005 0.0064 0.0064 0.0069 0.0094 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. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, your expenses would be higher.The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods; your investment has a 5% return each year; and the fund’s operating expenses remain the same. Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 70 221 384 859 96 300 520 1155 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. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 2% of the average value of its portfolio. 0.02 Principal Investment Strategies The fund is designed to provide diversification among different asset classes by investing its assets in other mutual funds advised by MFS (Massachusetts Financial Services Company, the fund’s investment adviser), referred to as underlying funds. MFS selects the asset class allocations based on a strategic asset allocation process that takes into account a variety of factors, including historical risk and performance, projected performance, and other factors. MFS’ analyses of projected performance are primarily based on quantitative models using various inputs such as valuation metrics, growth rates, profitability, yields, and inflation. MFS may also consider current market conditions, its qualitative assessment of the risk/return characteristics of asset classes, and other factors in determining these allocations.MFS employs the strategic asset allocation process described above to determine the amount of the fund's assets invested in (1) underlying funds that invest primarily in equity securities (“Equity Funds”) and underlying funds that provide exposure to less traditional asset classes, such as real estate (“Non-Traditional Funds”) and (2) underlying funds that invest primarily in debt instruments (“Bond Funds”) and an underlying fund that invests in cash and/or cash equivalents (“Money Market Fund”). MFS selects the underlying funds within each asset class based on underlying fund classifications, historical risk, historical and projected performance of the represented asset classes, as well as other factors.Within the Equity Fund allocation, MFS seeks to diversify by geography (by including domestic and international underlying funds), in terms of market capitalization (by including large, mid, and small capitalization underlying funds), and by style (by including both growth and value underlying funds). A portion of the fund’s assets is also allocated to Non-Traditional Funds (i.e., asset classes less correlated to the overall equity and debt markets), which MFS believes provides further diversification benefits.Within the Bond Fund allocation, MFS includes underlying funds with varying degrees of geographic, interest rate, and credit exposure, including exposure to below investment grade quality debt instruments. A portion of the fund’s assets may also be allocated to the Money Market Fund.MFS normally invests the underlying funds’ assets across different industries, sectors, countries, and regions, but MFS may invest a significant percentage of the underlying funds' assets in issuers in a single industry, sector, country, or region. As of April 1, 2025, the fund’s approximate long-term strategic allocation among asset classes was:<table cellpadding="0" cellspacing="0" style="border-collapse:collapse" width="100%"><tr style="font-size:1pt;"><td style="width:73.84%;"> </td><td style="width:26.16%;"> </td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Equity Funds and Non-Traditional Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">40%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Bond Funds and Money Market Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">60%</td></tr></table>All percentages are rounded to the nearest percent. MFS may deviate from the long-term strategic allocations set forth above; however, any deviation from the long-term strategic allocation is not expected to be greater than plus or minus 10% under normal market conditions. Additionally, the fund’s allocation to Non-Traditional Funds will not typically exceed 20% of the fund’s assets.As of April 1, 2025, the fund’s approximate strategic allocation among asset classes was:<table cellpadding="0" cellspacing="0" style="-sec-ix-redline:true;border-collapse:collapse" width="100%"><tr style="font-size:1pt;"><td style="width:73.84%;"> </td><td style="width:26.16%;"> </td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Equity Funds and Non-Traditional Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">38.5%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">U.S. Equity Funds</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">27.5%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">International Equity Funds</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">9.0%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Non-Traditional Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">2.0%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Bond Funds and Money Market Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">61.5%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Bond Funds</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">59.0%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Money Market Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">2.5%</td></tr></table>All percentages are rounded to the nearest tenth of a percent. As a result, the sum of the asset class allocations presented in the table may not total 100%. Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.The principal risks of investing in the fund are: Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Allocation Risk: MFS' assessment of the risk/return potential of asset classes and underlying funds, and the resulting allocation among asset classes and underlying funds, may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. Underlying Funds Risk: MFS' strategy of investing in underlying funds exposes the fund to the risks of the underlying funds. Each underlying fund pursues its own investment objective and strategies and may not achieve its objective. In addition to the fees and expenses the fund bears directly, shareholders of the fund will indirectly bear the fees and expenses of the underlying funds. Investment Selection Risk: MFS' investment analysis, its development and use of quantitative models, and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. The quantitative models used by MFS (both proprietary and third-party) may not produce the intended results for a variety of reasons, including the factors used in the models, the weight placed on each factor in the models, changes from the market factors' historical trends, changing sources of market return or market risk, and technical issues in the design, development, implementation, application, and maintenance of the models (e.g., incomplete, stale, or inaccurate data, human error, programming or other software issues, coding errors, and technology failures). Debt Market Risk: Debt markets can be volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument, issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced liquidity in a debt market or segment of a debt market. Interest Rate Risk: In general, the price of a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk is generally greater for instruments with longer maturities or durations, or that do not pay current interest. Credit Risk: The price of a debt instrument depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer, borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic stress, which in turn could negatively affect the market value and liquidity of a debt instrument.Below investment grade quality debt instruments (commonly referred to as “high yield securities” or “junk bonds”) can involve a substantially greater risk of default or can already be in default, and their values can decline significantly. Below investment grade quality debt instruments are regarded as having predominantly speculative characteristics. Below investment grade quality debt instruments tend to be more sensitive to adverse news about the issuer, or the market or economy in general, than higher quality debt instruments. Prepayment/Extension Risk: Instruments subject to prepayment and/or extension can reduce the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential for loss if the maturity of the instrument is extended. Inflation-Adjusted Debt Instruments Risk: Interest payments on inflation-adjusted debt instruments can be unpredictable and vary based on the level of inflation. If inflation is negative, principal and income can both decline. Equity Market Risk/Company Risk: Equity markets are volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the equity markets in general. Certain events can have a dramatic adverse effect on equity markets and may lead to periods of high volatility in an equity market or a segment of an equity market. The value of an investment held by the fund may decline due to factors directly related to the issuer. Growth Company Risk: The stocks of growth companies can be more sensitive to the company’s earnings and more volatile than the market in general. Value Company Risk: The stocks of value companies can continue to be undervalued for long periods of time and not realize their expected value and can be more volatile than the market in general. Intrinsic Value Strategy Risk: The stocks of companies that MFS believes are undervalued compared to their intrinsic value can continue to be undervalued for long periods of time, may not realize their expected value, and can be volatile. Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries, and regions to which the fund is exposed. Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to emerging markets or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market. Emerging Markets Risk: Investments tied economically to emerging markets, especially frontier markets, can involve additional and greater risks than the risks associated with investments in developed markets. Emerging markets can have less developed markets, greater custody and operational risk, less developed legal, regulatory, and accounting systems, greater government involvement in the economy, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater political, social, geopolitical, and economic instability than developed markets. Currency Risk: The value of foreign currencies relative to the U.S. dollar fluctuates in response to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions, and changes in currency exchange rates impact the financial condition of companies or other issuers and may change the value in U.S. dollars of investments denominated in foreign currencies. Real Estate-Related Investment Risk: The risks of investing in real estate-related securities include certain risks associated with the direct ownership of real estate and the real estate industry in general. These include risks related to general, regional and local economic conditions; difficulties in valuing and disposing of real estate; fluctuations in interest rates and property tax rates; shifts in zoning laws, environmental regulations and other governmental action; cash flow dependency; increased operating expenses; lack of availability of mortgage funds; losses due to natural disasters; overbuilding; losses due to casualty or condemnation; changes in property values and rental rates; the management skill and creditworthiness of the real estate investment trust (REIT) manager; and other factors. The securities of smaller real estate-related issuers can be more volatile and less liquid than securities of larger issuers and their issuers can have more limited financial resources. When-Issued, Delayed Delivery, and Forward Commitment Transaction Risk: The purchaser in a when-issued, delayed delivery or forward commitment transaction assumes the rights and risks of ownership, including the risks of price and yield fluctuations and the risk that the security will not be issued or delivered as anticipated. When-issued, delayed delivery, and forward commitment transactions can involve leverage. To be announced (TBA) transactions may significantly increase the fund's portfolio turnover rate. Derivatives Risk: Derivatives can be highly volatile and involve risks in addition to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage. Leveraging Risk: Leverage involves investment exposure in an amount exceeding the initial investment. Leverage can cause increased volatility by magnifying gains or losses. Counterparty and Third Party Risk: Transactions involving a counterparty or third party other than the issuer of the instrument are subject to the credit risk of the counterparty or third party, and to the counterparty’s or third party’s ability or willingness to perform in accordance with the terms of the transaction. Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs. Large Shareholder Risk: From time to time, shareholders of the fund (which may include institutional investors, financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund shares. These transactions may cause the fund to sell securities or invest additional cash, as the case may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance to the extent that it takes time to invest new cash and the fund maintains a larger cash position than it ordinarily would. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests.The fund’s past performance does not necessarily indicate how the fund will perform in the future. Updated performance is available at mfs.com or by calling 1-877-411-3325. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, they would reduce the returns shown. The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests. The fund’s past performance does not necessarily indicate how the fund will perform in the future. mfs.com 1-877-411-3325 Initial Class Bar Chart. The total return for the three-month period ended March 31, 2025, was 1.04%. During the period(s) shown in the bar chart, the highest quarterly return was 10.49% (for the calendar quarter ended June 30, 2020) and the lowest quarterly return was (9.41)% (for the calendar quarter ended June 30, 2022). The total return for the three-month period ended 2025-03-31 0.0104 highest quarterly return 0.1049 2020-06-30 lowest quarterly return -0.0941 2022-06-30 Performance Table. Average Annual Total Returns (For the Periods Ended December 31, 2024) 0.0586 0.0352 0.0468 0.0565 0.0326 0.0441 Reflects no deduction for fees, expenses, or taxes Reflects no deduction for fees, expenses, or taxes Bloomberg U.S. Aggregate Bond Index 0.0125 -0.0033 0.0135 MFS Conservative Allocation Portfolio Blended Index 0.0801 0.0441 0.0514 As of December 31, 2024, the MFS Conservative Allocation Portfolio Blended Index (the Blended Index) consisted of the following indices and weightings: 29% Standard & Poor’s 500 Stock Index; 9% MSCI EAFE (Europe, Australasia, Far East) Index (net div); 2% FTSE EPRA Nareit Developed Real Estate Index (net div); and 60% Bloomberg U.S. Aggregate Bond Index. The components and weightings of the Blended Index may have differed during the periods and may differ in the future. As of December 31, 2024, the MFS Conservative Allocation Portfolio Blended Index (the Blended Index) consisted of the following indices and weightings: 29% Standard & Poor’s 500 Stock Index; 9% MSCI EAFE (Europe, Australasia, Far East) Index (net div); 2% FTSE EPRA Nareit Developed Real Estate Index (net div); and 60% Bloomberg U.S. Aggregate Bond Index. The components and weightings of the Blended Index may have differed during the periods and may differ in the future. MFS® Growth Allocation Portfolio Summary of Key Information N/A N/A Investment Objective The fund's investment objective is to seek a high level of total return consistent with a greater than moderate level of risk relative to the other MFS Asset Allocation Portfolios. (The MFS Asset Allocation Portfolios currently are MFS Conservative Allocation Portfolio, MFS Moderate Allocation Portfolio, and MFS Growth Allocation Portfolio.) Fees and Expenses This table describes the fees and expenses that you may pay when you hold shares of the fund. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which the fund is offered were included, your expenses would be higher. Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): 0.0000 0.0000 0 0.0025 0.0004 0.0004 0.0075 0.0075 0.0079 0.0104 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. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, your expenses would be higher.The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods; your investment has a 5% return each year; and the fund’s operating expenses remain the same. Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 81 252 439 978 106 331 574 1271 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. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 12% of the average value of its portfolio. 0.12 Principal Investment Strategies The fund is designed to provide diversification among different asset classes by investing its assets in other mutual funds advised by MFS (Massachusetts Financial Services Company, the fund’s investment adviser), referred to as underlying funds. MFS selects the asset class allocations based on a strategic asset allocation process that takes into account a variety of factors, including historical risk and performance, projected performance, and other factors. MFS’ analyses of projected performance are primarily based on quantitative models using various inputs such as valuation metrics, growth rates, profitability, yields, and inflation. MFS may also consider current market conditions, its qualitative assessment of the risk/return characteristics of asset classes, and other factors in determining these allocations.MFS employs the strategic asset allocation process described above to determine the amount of the fund's assets invested in (1) underlying funds that invest primarily in equity securities (“Equity Funds”) and underlying funds that provide exposure to less traditional asset classes, such as real estate (“Non-Traditional Funds”) and (2) underlying funds that invest primarily in debt instruments (“Bond Funds”) and an underlying fund that invests in cash and/or cash equivalents (“Money Market Fund”). MFS selects the underlying funds within each asset class based on underlying fund classifications, historical risk, historical and projected performance of the represented asset classes, as well as other factors.Within the Equity Fund allocation, MFS seeks to diversify by geography (by including domestic and international underlying funds), in terms of market capitalization (by including large, mid, and small capitalization underlying funds), and by style (by including both growth and value underlying funds). A portion of the fund’s assets is also allocated to Non-Traditional Funds (i.e., asset classes less correlated to the overall equity and debt markets), which MFS believes provides further diversification benefits.Within the Bond Fund allocation, MFS includes underlying funds with varying degrees of geographic, interest rate, and credit exposure, including exposure to below investment grade quality debt instruments. A portion of the fund’s assets may also be allocated to the Money Market Fund.MFS normally invests the underlying funds’ assets across different industries, sectors, countries, and regions, but MFS may invest a significant percentage of the underlying funds' assets in issuers in a single industry, sector, country, or region. As of April 1, 2025, the fund’s approximate long-term strategic allocation among asset classes was:<table cellpadding="0" cellspacing="0" style="border-collapse:collapse" width="100%"><tr style="font-size:1pt;"><td style="width:73.84%;"> </td><td style="width:26.16%;"> </td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Equity Funds and Non-Traditional Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">80%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Bond Funds and Money Market Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">20%</td></tr></table>All percentages are rounded to the nearest percent. MFS may deviate from the long-term strategic allocations set forth above; however, any deviation from the long-term strategic allocation is not expected to be greater than plus or minus 10% under normal market conditions. Additionally, the fund’s allocation to Non-Traditional Funds will not typically exceed 20% of the fund’s assets.As of April 1, 2025, the fund’s approximate strategic allocation among asset classes was:<table cellpadding="0" cellspacing="0" style="-sec-ix-redline:true;border-collapse:collapse" width="100%"><tr style="font-size:1pt;"><td style="width:73.84%;"> </td><td style="width:26.16%;"> </td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Equity Funds and Non-Traditional Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">78.5%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">U.S. Equity Funds</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">52.5%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">International Equity Funds</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">21.0%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Non-Traditional Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">5.0%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Bond Funds and Money Market Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">21.5%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Bond Funds</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">19.5%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Money Market Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">2.0%</td></tr></table>All percentages are rounded to the nearest tenth of a percent. As a result, the sum of the asset class allocations presented in the table may not total 100%. Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.The principal risks of investing in the fund are: Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Allocation Risk: MFS' assessment of the risk/return potential of asset classes and underlying funds, and the resulting allocation among asset classes and underlying funds, may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. Underlying Funds Risk: MFS' strategy of investing in underlying funds exposes the fund to the risks of the underlying funds. Each underlying fund pursues its own investment objective and strategies and may not achieve its objective. In addition to the fees and expenses the fund bears directly, shareholders of the fund will indirectly bear the fees and expenses of the underlying funds. Investment Selection Risk: MFS' investment analysis, its development and use of quantitative models, and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. The quantitative models used by MFS (both proprietary and third-party) may not produce the intended results for a variety of reasons, including the factors used in the models, the weight placed on each factor in the models, changes from the market factors' historical trends, changing sources of market return or market risk, and technical issues in the design, development, implementation, application, and maintenance of the models (e.g., incomplete, stale, or inaccurate data, human error, programming or other software issues, coding errors, and technology failures). Equity Market Risk/Company Risk: Equity markets are volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the equity markets in general. Certain events can have a dramatic adverse effect on equity markets and may lead to periods of high volatility in an equity market or a segment of an equity market. The value of an investment held by the fund may decline due to factors directly related to the issuer. Growth Company Risk: The stocks of growth companies can be more sensitive to the company’s earnings and more volatile than the market in general. Value Company Risk: The stocks of value companies can continue to be undervalued for long periods of time and not realize their expected value and can be more volatile than the market in general. Intrinsic Value Strategy Risk: The stocks of companies that MFS believes are undervalued compared to their intrinsic value can continue to be undervalued for long periods of time, may not realize their expected value, and can be volatile. Debt Market Risk: Debt markets can be volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument, issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced liquidity in a debt market or segment of a debt market. Interest Rate Risk: In general, the price of a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk is generally greater for instruments with longer maturities or durations, or that do not pay current interest. Credit Risk: The price of a debt instrument depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer, borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic stress, which in turn could negatively affect the market value and liquidity of a debt instrument.Below investment grade quality debt instruments (commonly referred to as “high yield securities” or “junk bonds”) can involve a substantially greater risk of default or can already be in default, and their values can decline significantly. Below investment grade quality debt instruments are regarded as having predominantly speculative characteristics. Below investment grade quality debt instruments tend to be more sensitive to adverse news about the issuer, or the market or economy in general, than higher quality debt instruments. Prepayment/Extension Risk: Instruments subject to prepayment and/or extension can reduce the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential for loss if the maturity of the instrument is extended. Inflation-Adjusted Debt Instruments Risk: Interest payments on inflation-adjusted debt instruments can be unpredictable and vary based on the level of inflation. If inflation is negative, principal and income can both decline. Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries, and regions to which the fund is exposed. Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to emerging markets or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market. Emerging Markets Risk: Investments tied economically to emerging markets, especially frontier markets, can involve additional and greater risks than the risks associated with investments in developed markets. Emerging markets can have less developed markets, greater custody and operational risk, less developed legal, regulatory, and accounting systems, greater government involvement in the economy, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater political, social, geopolitical, and economic instability than developed markets. Currency Risk: The value of foreign currencies relative to the U.S. dollar fluctuates in response to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions, and changes in currency exchange rates impact the financial condition of companies or other issuers and may change the value in U.S. dollars of investments denominated in foreign currencies. Real Estate-Related Investment Risk: The risks of investing in real estate-related securities include certain risks associated with the direct ownership of real estate and the real estate industry in general. These include risks related to general, regional and local economic conditions; difficulties in valuing and disposing of real estate; fluctuations in interest rates and property tax rates; shifts in zoning laws, environmental regulations and other governmental action; cash flow dependency; increased operating expenses; lack of availability of mortgage funds; losses due to natural disasters; overbuilding; losses due to casualty or condemnation; changes in property values and rental rates; the management skill and creditworthiness of the real estate investment trust (REIT) manager; and other factors. The securities of smaller real estate-related issuers can be more volatile and less liquid than securities of larger issuers and their issuers can have more limited financial resources. When-Issued, Delayed Delivery, and Forward Commitment Transaction Risk: The purchaser in a when-issued, delayed delivery or forward commitment transaction assumes the rights and risks of ownership, including the risks of price and yield fluctuations and the risk that the security will not be issued or delivered as anticipated. When-issued, delayed delivery, and forward commitment transactions can involve leverage. To be announced (TBA) transactions may significantly increase the fund's portfolio turnover rate. Derivatives Risk: Derivatives can be highly volatile and involve risks in addition to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage. Leveraging Risk: Leverage involves investment exposure in an amount exceeding the initial investment. Leverage can cause increased volatility by magnifying gains or losses. Counterparty and Third Party Risk: Transactions involving a counterparty or third party other than the issuer of the instrument are subject to the credit risk of the counterparty or third party, and to the counterparty’s or third party’s ability or willingness to perform in accordance with the terms of the transaction. Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs. Large Shareholder Risk: From time to time, shareholders of the fund (which may include institutional investors, financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund shares. These transactions may cause the fund to sell securities or invest additional cash, as the case may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance to the extent that it takes time to invest new cash and the fund maintains a larger cash position than it ordinarily would. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests.The fund’s past performance does not necessarily indicate how the fund will perform in the future. Updated performance is available at mfs.com or by calling 1-877-411-3325. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, they would reduce the returns shown. The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests. The fund’s past performance does not necessarily indicate how the fund will perform in the future. mfs.com 1-877-411-3325 Initial Class Bar Chart. The total return for the three-month period ended March 31, 2025, was (0.40)%. During the period(s) shown in the bar chart, the highest quarterly return was 16.78% (for the calendar quarter ended June 30, 2020) and the lowest quarterly return was (16.60)% (for the calendar quarter ended March 31, 2020). The total return for the three-month period ended 2025-03-31 highest quarterly return 0.1678 2020-06-30 lowest quarterly return -0.1660 2020-03-31 Performance Table. Average Annual Total Returns (For the Periods Ended December 31, 2024) 0.1034 0.0686 0.0803 0.1005 0.0660 0.0777 Reflects no deduction for fees, expenses, or taxes Reflects no deduction for fees, expenses, or taxes Standard & Poor's 500 Stock Index 0.2502 0.1453 0.1310 MFS Growth Allocation Portfolio Blended Index 0.1422 0.0878 0.0864 As of December 31, 2024, the MFS Growth Allocation Portfolio Blended Index (the Blended Index) consisted of the following indices and weightings: 54% Standard & Poor’s 500 Stock Index; 21% MSCI EAFE (Europe, Australasia, Far East) Index (net div); 5% FTSE EPRA Nareit Developed Real Estate Index (net div); and 20% Bloomberg U.S. Aggregate Bond Index. The components and weightings of the Blended Index may have differed during the periods and may differ in the future. As of December 31, 2024, the MFS Growth Allocation Portfolio Blended Index (the Blended Index) consisted of the following indices and weightings: 54% Standard & Poor’s 500 Stock Index; 21% MSCI EAFE (Europe, Australasia, Far East) Index (net div); 5% FTSE EPRA Nareit Developed Real Estate Index (net div); and 20% Bloomberg U.S. Aggregate Bond Index. The components and weightings of the Blended Index may have differed during the periods and may differ in the future. MFS® Moderate Allocation Portfolio Summary of Key Information N/A N/A Investment Objective The fund's investment objective is to seek a high level of total return consistent with a moderate level of risk relative to the other MFS Asset Allocation Portfolios. (The MFS Asset Allocation Portfolios currently are MFS Conservative Allocation Portfolio, MFS Moderate Allocation Portfolio, and MFS Growth Allocation Portfolio.) Fees and Expenses This table describes the fees and expenses that you may pay when you hold shares of the fund. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which the fund is offered were included, your expenses would be higher. Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): 0.0000 0.0000 0 0.0025 0.0002 0.0002 0.0069 0.0069 0.0071 0.0096 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. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, your expenses would be higher.The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods; your investment has a 5% return each year; and the fund’s operating expenses remain the same. Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 73 227 395 883 98 306 531 1178 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. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 2% of the average value of its portfolio. 0.02 Principal Investment Strategies The fund is designed to provide diversification among different asset classes by investing its assets in other mutual funds advised by MFS (Massachusetts Financial Services Company, the fund’s investment adviser), referred to as underlying funds. MFS selects the asset class allocations based on a strategic asset allocation process that takes into account a variety of factors, including historical risk and performance, projected performance, and other factors. MFS’ analyses of projected performance are primarily based on quantitative models using various inputs such as valuation metrics, growth rates, profitability, yields, and inflation. MFS may also consider current market conditions, its qualitative assessment of the risk/return characteristics of asset classes, and other factors in determining these allocations.MFS employs the strategic asset allocation process described above to determine the amount of the fund's assets invested in (1) underlying funds that invest primarily in equity securities (“Equity Funds”) and underlying funds that provide exposure to less traditional asset classes, such as real estate (“Non-Traditional Funds”) and (2) underlying funds that invest primarily in debt instruments (“Bond Funds”) and an underlying fund that invests in cash and/or cash equivalents (“Money Market Fund”). MFS selects the underlying funds within each asset class based on underlying fund classifications, historical risk, historical and projected performance of the represented asset classes, as well as other factors.Within the Equity Fund allocation, MFS seeks to diversify by geography (by including domestic and international underlying funds), in terms of market capitalization (by including large, mid, and small capitalization underlying funds), and by style (by including both growth and value underlying funds). A portion of the fund’s assets is also allocated to Non-Traditional Funds (i.e., asset classes less correlated to the overall equity and debt markets), which MFS believes provides further diversification benefits.Within the Bond Fund allocation, MFS includes underlying funds with varying degrees of geographic, interest rate, and credit exposure, including exposure to below investment grade quality debt instruments. A portion of the fund’s assets may also be allocated to the Money Market Fund.MFS normally invests the underlying funds’ assets across different industries, sectors, countries, and regions, but MFS may invest a significant percentage of the underlying funds' assets in issuers in a single industry, sector, country, or region. As of April 1, 2025, the fund’s approximate long-term strategic allocation among asset classes was:<table cellpadding="0" cellspacing="0" style="border-collapse:collapse" width="100%"><tr style="font-size:1pt;"><td style="width:73.84%;"> </td><td style="width:26.16%;"> </td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Equity Funds and Non-Traditional Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">60%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Bond Funds and Money Market Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">40%</td></tr></table>All percentages are rounded to the nearest percent. MFS may deviate from the long-term strategic allocations set forth above; however, any deviation from the long-term strategic allocation is not expected to be greater than plus or minus 10% under normal market conditions. Additionally, the fund’s allocation to Non-Traditional Funds will not typically exceed 20% of the fund’s assets.As of April 1, 2025, the fund’s approximate strategic allocation among asset classes was:<table cellpadding="0" cellspacing="0" style="-sec-ix-redline:true;border-collapse:collapse" width="100%"><tr style="font-size:1pt;"><td style="width:73.84%;"> </td><td style="width:26.16%;"> </td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Equity Funds and Non-Traditional Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">58.5%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">U.S. Equity Funds</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">41.5%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">International Equity Funds</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">14.0%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Non-Traditional Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">3.0%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Bond Funds and Money Market Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">41.5%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Bond Funds</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">39.0%</td></tr><tr><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-right:0.5pt; border-right-style:solid; border-right-color:#000000;">Money Market Fund</td><td style="vertical-align:bottom; border-bottom:0.5pt; border-bottom-style:solid; border-bottom-color:#000000; border-top:0.5pt; border-top-style:solid; border-top-color:#000000; border-left:0.5pt; border-left-style:solid; border-left-color:#000000;">2.5%</td></tr></table>All percentages are rounded to the nearest tenth of a percent. As a result, the sum of the asset class allocations presented in the table may not total 100%. Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.The principal risks of investing in the fund are: Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Allocation Risk: MFS' assessment of the risk/return potential of asset classes and underlying funds, and the resulting allocation among asset classes and underlying funds, may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. Underlying Funds Risk: MFS' strategy of investing in underlying funds exposes the fund to the risks of the underlying funds. Each underlying fund pursues its own investment objective and strategies and may not achieve its objective. In addition to the fees and expenses the fund bears directly, shareholders of the fund will indirectly bear the fees and expenses of the underlying funds. Investment Selection Risk: MFS' investment analysis, its development and use of quantitative models, and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. The quantitative models used by MFS (both proprietary and third-party) may not produce the intended results for a variety of reasons, including the factors used in the models, the weight placed on each factor in the models, changes from the market factors' historical trends, changing sources of market return or market risk, and technical issues in the design, development, implementation, application, and maintenance of the models (e.g., incomplete, stale, or inaccurate data, human error, programming or other software issues, coding errors, and technology failures). Equity Market Risk/Company Risk: Equity markets are volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the equity markets in general. Certain events can have a dramatic adverse effect on equity markets and may lead to periods of high volatility in an equity market or a segment of an equity market. The value of an investment held by the fund may decline due to factors directly related to the issuer. Growth Company Risk: The stocks of growth companies can be more sensitive to the company’s earnings and more volatile than the market in general. Value Company Risk: The stocks of value companies can continue to be undervalued for long periods of time and not realize their expected value and can be more volatile than the market in general. Intrinsic Value Strategy Risk: The stocks of companies that MFS believes are undervalued compared to their intrinsic value can continue to be undervalued for long periods of time, may not realize their expected value, and can be volatile. Debt Market Risk: Debt markets can be volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument, issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced liquidity in a debt market or segment of a debt market. Interest Rate Risk: In general, the price of a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk is generally greater for instruments with longer maturities or durations, or that do not pay current interest. Credit Risk: The price of a debt instrument depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer, borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic stress, which in turn could negatively affect the market value and liquidity of a debt instrument.Below investment grade quality debt instruments (commonly referred to as “high yield securities” or “junk bonds”) can involve a substantially greater risk of default or can already be in default, and their values can decline significantly. Below investment grade quality debt instruments are regarded as having predominantly speculative characteristics. Below investment grade quality debt instruments tend to be more sensitive to adverse news about the issuer, or the market or economy in general, than higher quality debt instruments. Prepayment/Extension Risk: Instruments subject to prepayment and/or extension can reduce the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential for loss if the maturity of the instrument is extended. Inflation-Adjusted Debt Instruments Risk: Interest payments on inflation-adjusted debt instruments can be unpredictable and vary based on the level of inflation. If inflation is negative, principal and income can both decline. Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries, and regions to which the fund is exposed. Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to emerging markets or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market. Emerging Markets Risk: Investments tied economically to emerging markets, especially frontier markets, can involve additional and greater risks than the risks associated with investments in developed markets. Emerging markets can have less developed markets, greater custody and operational risk, less developed legal, regulatory, and accounting systems, greater government involvement in the economy, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater political, social, geopolitical, and economic instability than developed markets. Currency Risk: The value of foreign currencies relative to the U.S. dollar fluctuates in response to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions, and changes in currency exchange rates impact the financial condition of companies or other issuers and may change the value in U.S. dollars of investments denominated in foreign currencies. Real Estate-Related Investment Risk: The risks of investing in real estate-related securities include certain risks associated with the direct ownership of real estate and the real estate industry in general. These include risks related to general, regional and local economic conditions; difficulties in valuing and disposing of real estate; fluctuations in interest rates and property tax rates; shifts in zoning laws, environmental regulations and other governmental action; cash flow dependency; increased operating expenses; lack of availability of mortgage funds; losses due to natural disasters; overbuilding; losses due to casualty or condemnation; changes in property values and rental rates; the management skill and creditworthiness of the real estate investment trust (REIT) manager; and other factors. The securities of smaller real estate-related issuers can be more volatile and less liquid than securities of larger issuers and their issuers can have more limited financial resources. When-Issued, Delayed Delivery, and Forward Commitment Transaction Risk: The purchaser in a when-issued, delayed delivery or forward commitment transaction assumes the rights and risks of ownership, including the risks of price and yield fluctuations and the risk that the security will not be issued or delivered as anticipated. When-issued, delayed delivery, and forward commitment transactions can involve leverage. To be announced (TBA) transactions may significantly increase the fund's portfolio turnover rate. Derivatives Risk: Derivatives can be highly volatile and involve risks in addition to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage. Leveraging Risk: Leverage involves investment exposure in an amount exceeding the initial investment. Leverage can cause increased volatility by magnifying gains or losses. Counterparty and Third Party Risk: Transactions involving a counterparty or third party other than the issuer of the instrument are subject to the credit risk of the counterparty or third party, and to the counterparty’s or third party’s ability or willingness to perform in accordance with the terms of the transaction. Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs. Large Shareholder Risk: From time to time, shareholders of the fund (which may include institutional investors, financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund shares. These transactions may cause the fund to sell securities or invest additional cash, as the case may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance to the extent that it takes time to invest new cash and the fund maintains a larger cash position than it ordinarily would. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests.The fund’s past performance does not necessarily indicate how the fund will perform in the future. Updated performance is available at mfs.com or by calling 1-877-411-3325. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, they would reduce the returns shown. The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests. The fund’s past performance does not necessarily indicate how the fund will perform in the future. mfs.com 1-877-411-3325 Initial Class Bar Chart. The total return for the three-month period ended March 31, 2025, was 0.27%. During the period(s) shown in the bar chart, the highest quarterly return was 13.62% (for the calendar quarter ended June 30, 2020) and the lowest quarterly return was (12.32)% (for the calendar quarter ended March 31, 2020). The total return for the three-month period ended 2025-03-31 0.0027 highest quarterly return 0.1362 2020-06-30 lowest quarterly return -0.1232 2020-03-31 Performance Table. Average Annual Total Returns (For the Periods Ended December 31, 2024) 0.0831 0.0538 0.0651 0.0812 0.0513 0.0625 Reflects no deduction for fees, expenses, or taxes Reflects no deduction for fees, expenses, or taxes Standard & Poor's 500 Stock Index 0.2502 0.1453 0.1310 MFS Moderate Allocation Portfolio Blended Index 0.1141 0.0684 0.0709 As of December 31, 2024, the MFS Moderate Allocation Portfolio Blended Index (the Blended Index) consisted of the following indices and weightings: 43% Standard & Poor’s 500 Stock Index; 14% MSCI EAFE (Europe, Australasia, Far East) Index (net div); 3% FTSE EPRA Nareit Developed Real Estate Index (net div); and 40% Bloomberg U.S. Aggregate Bond Index. The components and weightings of the Blended Index may have differed during the periods and may differ in the future. As of December 31, 2024, the MFS Moderate Allocation Portfolio Blended Index (the Blended Index) consisted of the following indices and weightings: 43% Standard & Poor’s 500 Stock Index; 14% MSCI EAFE (Europe, Australasia, Far East) Index (net div); 3% FTSE EPRA Nareit Developed Real Estate Index (net div); and 40% Bloomberg U.S. Aggregate Bond Index. The components and weightings of the Blended Index may have differed during the periods and may differ in the future. MFS® Mid Cap Value Portfolio Summary of Key Information N/A N/A Investment Objective The fund’s investment objective is to seek capital appreciation. Fees and Expenses This table describes the fees and expenses that you may pay when you hold shares of the fund. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which the fund is offered were included, your expenses would be higher. Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): 0.0075 0.0075 0 0.0025 0.0005 0.0005 0.0080 0.0105 -0.0001 -0.0001 0.0079 0.0104 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. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, your expenses would be higher.The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods; your investment has a 5% return each year; and the fund’s operating expenses remain the same. Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 81 254 443 989 106 333 578 1282 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. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 27% of the average value of its portfolio. 0.27 Principal Investment Strategies MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests at least 80% of the fund’s net assets in issuers with medium market capitalizations. MFS generally defines medium market capitalization issuers as issuers with market capitalizations similar to those of issuers included in the Russell Midcap® Value Index over the last 13 months at the time of purchase. As of March 31, 2025, the range of the market capitalizations of the issuers in the Russell Midcap® Value Index was between approximately $272.6 million and $88.3 billion. MFS normally invests the fund’s assets primarily in equity securities. Equity securities include common stocks, depositary receipts, equity interests in real estate investment trusts (REITs), and other securities that represent an ownership interest (or right to acquire an ownership interest) in a company or other issuer.MFS focuses on investing the fund's assets in the stocks of companies it believes are undervalued compared to their perceived worth (value companies). MFS may invest the fund’s assets in foreign securities. MFS normally invests the fund's assets across different industries and sectors, but MFS may invest a significant percentage of the fund's assets in issuers in a single industry or sector.MFS uses an active bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual issuers. Quantitative screening tools that systematically evaluate issuers may also be considered.For purposes of the fund's 80% policy, net assets include the amount of any borrowings for investment purposes. Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.The principal risks of investing in the fund are: Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Investment Selection Risk: MFS' investment analysis and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. In addition, to the extent MFS considers quantitative tools in managing the fund, such tools may not produce the intended results. Equity Market Risk/Company Risk: Equity markets are volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the equity markets in general. Certain events can have a dramatic adverse effect on equity markets and may lead to periods of high volatility in an equity market or a segment of an equity market. The value of an investment held by the fund may decline due to factors directly related to the issuer. Value Company Risk: The stocks of value companies can continue to be undervalued for long periods of time and not realize their expected value and can be more volatile than the market in general. Mid Cap Risk: The stocks of mid cap companies can be more volatile and their shares can be less liquid than those of larger companies. Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to countries with developing economies or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market. REITs Risk: The risks of investing in REITs include certain risks associated with the direct ownership of real estate and the real estate industry in general. These include risks related to general, regional and local economic conditions; difficulties in valuing and disposing of real estate; fluctuations in interest rates and property tax rates; shifts in zoning laws, environmental regulations and other governmental action; cash flow dependency; increased operating expenses; lack of availability of mortgage funds; losses due to natural disasters; overbuilding; losses due to casualty or condemnation; changes in property values and rental rates; the management skill and creditworthiness of the REIT manager; and other factors. The securities of smaller real estate-related issuers can be more volatile and less liquid than securities of larger issuers and their issuers can have more limited financial resources. Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries, and regions to which the fund is exposed. Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs. Large Shareholder Risk: From time to time, shareholders of the fund (which may include institutional investors, financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund shares. These transactions may cause the fund to sell securities or invest additional cash, as the case may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance to the extent that it takes time to invest new cash and the fund maintains a larger cash position than it ordinarily would. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests.The fund’s past performance does not necessarily indicate how the fund will perform in the future. Updated performance is available at mfs.com or by calling 1-877-411-3325. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, they would reduce the returns shown. The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests. The fund’s past performance does not necessarily indicate how the fund will perform in the future. mfs.com 1-877-411-3325 Initial Class Bar Chart. The total return for the three-month period ended March 31, 2025, was (2.64)%. During the period(s) shown in the bar chart, the highest quarterly return was 19.90% (for the calendar quarter ended June 30, 2020) and the lowest quarterly return was (31.01)% (for the calendar quarter ended March 31, 2020). The total return for the three-month period ended 2025-03-31 highest quarterly return 0.1990 2020-06-30 lowest quarterly return -0.3101 2020-03-31 Performance Table. Average Annual Total Returns (For the Periods Ended December 31, 2024) 0.1375 0.0974 0.0905 0.1352 0.0947 0.0878 Reflects no deduction for fees, expenses, or taxes Reflects no deduction for fees, expenses, or taxes Russell 3000® Index 0.2381 0.1386 0.1255 Russell Midcap® Value Index 0.1307 0.0859 0.0810 MFS® Inflation-Adjusted Bond Portfolio Summary of Key Information N/A N/A Investment Objective The fund’s investment objective is to seek total return that exceeds the rate of inflation over the long-term, with an emphasis on current income, but also considering capital appreciation. Fees and Expenses This table describes the fees and expenses that you may pay when you hold shares of the fund. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which the fund is offered were included, your expenses would be higher. Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): 0.0050 0.0050 0 0.0025 0.0011 0.0011 0.0061 0.0086 -0.0001 -0.0001 0.0060 0.0085 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. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, your expenses would be higher.The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods; your investment has a 5% return each year; and the fund’s operating expenses remain the same. Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 61 194 339 761 87 273 476 1060 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. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 43% of the average value of its portfolio. 0.43 Principal Investment Strategies MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests at least 80% of the fund’s net assets in inflation-adjusted debt instruments and other instruments with similar economic characteristics. MFS generally focuses the fund’s investments in inflation-adjusted debt instruments issued by U.S. and foreign governments. MFS may also invest the fund’s assets in inflation-adjusted debt instruments of other issuers, other instruments with similar economic characteristics to these instruments, including derivatives, and non-inflation-adjusted debt instruments.MFS primarily invests the fund’s assets in investment grade quality debt instruments, but may also invest the fund’s assets in below investment grade quality debt instruments. MFS invests the fund’s assets in U.S. and foreign securities.MFS normally invests the fund's assets across different countries and regions, but MFS may invest a significant percentage of the fund's assets in issuers in a single country or region.The fund is a non-diversified fund. This means that MFS may invest a significant percentage of the fund’s assets in a single issuer or a small number of issuers. While MFS may use derivatives for any investment purpose, to the extent MFS uses derivatives, MFS expects to use derivatives primarily to increase or decrease exposure to a particular market, segment of the market, or security, to increase or decrease interest rate or currency exposure, or as alternatives to direct investments. Derivatives include futures, forward contracts, options, and swaps.MFS allocates the fund’s assets across countries, maturities, and types of debt instruments based on its evaluation of U.S. and foreign macroeconomic factors, including interest rates, inflation rates, and monetary and fiscal policies.MFS uses an active bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual instruments and their issuers. Quantitative screening tools that systematically evaluate instruments may also be considered. In structuring the fund, MFS also considers top-down factors.For purposes of the fund's 80% policy, net assets include the amount of any borrowings for investment purposes. Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.The principal risks of investing in the fund are: Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Investment Selection Risk: MFS' investment analysis and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. In addition, to the extent MFS considers quantitative tools in managing the fund, such tools may not produce the intended results. Debt Market Risk: Debt markets can be volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument, issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced liquidity in a debt market or segment of a debt market. Interest Rate Risk: In general, the price of a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk is generally greater for instruments with longer maturities or durations, or that do not pay current interest. Credit Risk: The price of a debt instrument depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer, borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic stress, which in turn could negatively affect the market value and liquidity of a debt instrument.Below investment grade quality debt instruments (commonly referred to as “high yield securities” or “junk bonds”) can involve a substantially greater risk of default or can already be in default, and their values can decline significantly. Below investment grade quality debt instruments are regarded as having predominantly speculative characteristics. Below investment grade quality debt instruments tend to be more sensitive to adverse news about the issuer, or the market or economy in general, than higher quality debt instruments.Government securities not supported as to the payment of principal or interest by the full faith and credit of the government are subject to greater credit risk than are government securities supported by the full faith and credit of the government. Inflation-Adjusted Debt Instruments Risk: Interest payments on inflation-adjusted debt instruments can be unpredictable and vary based on the level of inflation. If inflation is negative, principal and income can both decline. Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to countries with developing economies, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market. Currency Risk: The value of foreign currencies relative to the U.S. dollar fluctuates in response to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions, and changes in currency exchange rates impact the financial condition of companies or other issuers and may change the value in U.S. dollars of investments denominated in foreign currencies. Focus Risk: Issuers in a single country or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the countries and regions to which the fund is exposed. Non-Diversification Risk: Because MFS may invest a significant percentage of the fund’s assets in a single issuer or small number of issuers, the fund’s performance could be closely tied to the value of that one issuer or issuers, and could be more volatile than the performance of diversified funds. Derivatives Risk: Derivatives can be highly volatile and involve risks in addition to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage. Leveraging Risk: Leverage involves investment exposure in an amount exceeding the initial investment. Leverage can cause increased volatility by magnifying gains or losses. Counterparty and Third Party Risk: Transactions involving a counterparty or third party other than the issuer of the instrument are subject to the credit risk of the counterparty or third party, and to the counterparty’s or third party’s ability or willingness to perform in accordance with the terms of the transaction. Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs. Large Shareholder Risk: From time to time, shareholders of the fund (which may include institutional investors, financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund shares. These transactions may cause the fund to sell securities or invest additional cash, as the case may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance to the extent that it takes time to invest new cash and the fund maintains a larger cash position than it ordinarily would. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests.The fund’s past performance does not necessarily indicate how the fund will perform in the future. Updated performance is available at mfs.com or by calling 1-877-411-3325. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, they would reduce the returns shown. The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests. The fund’s past performance does not necessarily indicate how the fund will perform in the future. mfs.com 1-877-411-3325 Initial Class Bar Chart. The total return for the three-month period ended March 31, 2025, was 3.63%. During the period(s) shown in the bar chart, the highest quarterly return was 8.49% (for the calendar quarter ended December 31, 2023) and the lowest quarterly return was (12.69)% (for the calendar quarter ended June 30, 2022). The total return for the three-month period ended 2025-03-31 0.0363 highest quarterly return 0.0849 2023-12-31 lowest quarterly return -0.1269 2022-06-30 Performance Table. Average Annual Total Returns (For the Periods Ended December 31, 2024) -0.0394 -0.0223 -0.0025 -0.0413 -0.0247 -0.0049 Reflects no deduction for fees, expenses, or taxes Reflects no deduction for fees, expenses, or taxes Bloomberg Global Aggregate Index -0.0169 -0.0196 0.0015 Bloomberg World Government Inflation-Linked Bond Index -0.0310 -0.0151 0.0034 MFS® Limited Maturity Portfolio Summary of Key Information N/A N/A Investment Objective The fund’s investment objective is to seek total return with an emphasis on current income, but also considering capital preservation. Fees and Expenses This table describes the fees and expenses that you may pay when you hold shares of the fund. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which the fund is offered were included, your expenses would be higher. Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): 0.0040 0.0040 0 0.0025 0.0009 0.0009 0.0049 0.0074 -0.0001 -0.0001 0.0048 0.0073 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. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, your expenses would be higher.The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods; your investment has a 5% return each year; and the fund’s operating expenses remain the same. Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 49 156 273 615 75 236 410 917 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. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 40% of the average value of its portfolio. 0.40 Principal Investment Strategies MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests the fund’s assets primarily in debt instruments. Debt instruments include U.S. Government securities, corporate bonds, foreign government securities, securitized instruments (including mortgage-backed securities and other asset-backed securities), and other obligations to repay money borrowed. The fund’s dollar-weighted average effective maturity will normally not exceed five years. MFS generally invests substantially all of the fund’s assets in investment grade quality debt instruments.MFS invests the fund’s assets in U.S. securities and U.S. dollar-denominated foreign securities.MFS normally invests the fund's assets across different industries, sectors, countries, and regions, but MFS may invest a significant percentage of the fund’s assets in issuers in a single industry, sector, country, or region. MFS may invest a significant percentage of the fund’s assets in a single issuer or a small number of issuers.While MFS may use derivatives for any investment purpose, to the extent MFS uses derivatives, MFS expects to use derivatives primarily to increase or decrease exposure to a particular market, segment of the market, or security, to increase or decrease interest rate exposure, or as alternatives to direct investments. Derivatives include futures, forward contracts, options, and swaps.MFS uses an active bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual instruments and their issuers. Quantitative screening tools that systematically evaluate instruments may also be considered. In structuring the fund, MFS also considers top-down factors. Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.The principal risks of investing in the fund are: Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Investment Selection Risk: MFS' investment analysis and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. In addition, to the extent MFS considers quantitative tools in managing the fund, such tools may not produce the intended results. Debt Market Risk: Debt markets can be volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument, issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced liquidity in a debt market or segment of a debt market. Interest Rate Risk: In general, the price of a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk is generally greater for instruments with longer maturities or durations, or that do not pay current interest. Credit Risk: The price of a debt instrument depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer, borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic stress, which in turn could negatively affect the market value and liquidity of a debt instrument. Foreign Risk: Exposure to foreign markets through issuers can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to countries with developing economies or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market. Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries, and regions to which the fund is exposed. If MFS invests a significant percentage of the fund's assets in a single issuer or small number of issuers, the fund’s performance could be more volatile than the performance of more diversified funds. Prepayment/Extension Risk: Instruments subject to prepayment and/or extension can reduce the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential for loss if the maturity of the instrument is extended. Derivatives Risk: Derivatives can be highly volatile and involve risks in addition to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage. Leveraging Risk: Leverage involves investment exposure in an amount exceeding the initial investment. Leverage can cause increased volatility by magnifying gains or losses. Counterparty and Third Party Risk: Transactions involving a counterparty or third party other than the issuer of the instrument are subject to the credit risk of the counterparty or third party, and to the counterparty’s or third party’s ability or willingness to perform in accordance with the terms of the transaction. Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs. Large Shareholder Risk: From time to time, shareholders of the fund (which may include institutional investors, financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund shares. These transactions may cause the fund to sell securities or invest additional cash, as the case may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance to the extent that it takes time to invest new cash and the fund maintains a larger cash position than it ordinarily would. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests.The fund’s past performance does not necessarily indicate how the fund will perform in the future. Updated performance is available at mfs.com or by calling 1-877-411-3325. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, they would reduce the returns shown. The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests. The fund’s past performance does not necessarily indicate how the fund will perform in the future. mfs.com 1-877-411-3325 Initial Class Bar Chart. The total return for the three-month period ended March 31, 2025, was 1.68%. During the period(s) shown in the bar chart, the highest quarterly return was 5.19% (for the calendar quarter ended June 30, 2020) and the lowest quarterly return was (3.09)% (for the calendar quarter ended March 31, 2020). The total return for the three-month period ended 2025-03-31 0.0168 highest quarterly return 0.0519 2020-06-30 lowest quarterly return -0.0309 2020-03-31 Performance Table. Average Annual Total Returns (For the Periods Ended December 31, 2024) 0.0530 0.0227 0.0217 0.0502 0.0203 0.0192 Reflects no deduction for fees, expenses, or taxes Reflects no deduction for fees, expenses, or taxes Bloomberg U.S. Aggregate Bond Index 0.0125 -0.0033 0.0135 Bloomberg 1-3 Year U.S. Government/Credit Bond Index 0.0436 0.0158 0.0163 MFS® Blended Research® Small Cap Equity Portfolio Summary of Key Information N/A N/A Investment Objective The fund’s investment objective is to seek capital appreciation. Fees and Expenses This table describes the fees and expenses that you may pay when you hold shares of the fund. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which the fund is offered were included, your expenses would be higher. Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): 0.0040 0.0040 0 0.0025 0.0018 0.0018 0.0058 0.0083 -0.0001 -0.0001 0.0057 0.0082 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. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, your expenses would be higher.The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods; your investment has a 5% return each year; and the fund’s operating expenses remain the same. Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 58 185 323 725 84 264 460 1024 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. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 66% of the average value of its portfolio. 0.66 Principal Investment Strategies MFS (Massachusetts Financial Services Company, the fund's investment adviser) seeks to achieve the fund's objective by actively identifying potential investments based on fundamental and quantitative analysis and then constructing a portfolio from these potential investments while managing various risk factors (e.g., issuer, industry, and sector weightings, market capitalization, and volatility) compared to the Russell 2000® Index, which represents the fund's investment universe. MFS normally invests at least 80% of the fund’s net assets in equity securities of issuers with small market capitalizations. MFS generally defines small market capitalization issuers as issuers with market capitalizations similar to those of issuers included in the Russell 2000® Index over the last 13 months at the time of purchase. As of March 31, 2025, the range of the market capitalizations of the issuers in the Russell 2000® Index was between approximately $5.2 million and $15.0 billion. Equity securities include common stocks, depositary receipts, equity interests in real estate investment trusts (REITs), and other securities that represent an ownership interest (or right to acquire an ownership interest) in a company or other issuer. In selecting investments for the fund, MFS is not constrained by any particular investment style. MFS may invest the fund’s assets in the stocks of companies it believes to have above average earnings growth potential compared to other companies (growth companies), in the stocks of companies it believes are undervalued compared to their perceived worth (value companies), or in a combination of growth and value companies. MFS may invest the fund’s assets in foreign securities. MFS normally invests the fund's assets across different industries and sectors, but MFS may invest a significant percentage of the fund's assets in issuers in a single industry or sector.MFS uses an active bottom-up approach to buying and selling investments for the fund. Investments are selected primarily based on blending fundamental and quantitative research. MFS uses fundamental analysis of individual issuers to determine a fundamental rating for an issuer. MFS uses quantitative analysis to determine a quantitative rating for an issuer. MFS combines the fundamental rating with the quantitative rating to create a blended rating for an issuer. When the fundamental rating is not available, MFS treats the issuer as having a neutral fundamental rating. MFS constructs the portfolio using a portfolio optimization process that considers the blended rating, as well as issuer, industry, and sector weightings, market capitalization, volatility, and other factors. The portfolio managers have the discretion to adjust the inputs and parameters used in the optimization process and the fund's portfolio holdings based on factors such as the desired portfolio characteristics and the portfolio managers’ qualitative assessment of the optimization results. MFS' goal is to construct an actively managed portfolio with a target predicted tracking error of approximately 3% compared to the Russell 2000® Index. Tracking error generally measures how the differences between the fund's returns and the Russell 2000® Index's returns have varied over a period of time. For purposes of the fund's 80% policy, net assets include the amount of any borrowings for investment purposes. Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.The principal risks of investing in the fund are: Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Investment Selection Risk: MFS' investment analysis, its development and use of quantitative models, and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. The quantitative models used by MFS (both proprietary and third-party) may not produce the intended results for a variety of reasons, including the factors used in the models, the weight placed on each factor in the models, changes from the market factors' historical trends, changing sources of market return or market risk, and technical issues in the design, development, implementation, application, and maintenance of the models (e.g., incomplete, stale, or inaccurate data, human error, programming or other software issues, coding errors, and technology failures). Equity Market Risk/Company Risk: Equity markets are volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the equity markets in general. Certain events can have a dramatic adverse effect on equity markets and may lead to periods of high volatility in an equity market or a segment of an equity market. The value of an investment held by the fund may decline due to factors directly related to the issuer. Small Cap Risk: The stocks of small cap companies can be more volatile and their shares can be less liquid than those of larger companies. Investment Strategy Risk: There is no assurance that the fund's predicted tracking error will equal its target predicted tracking error at any point in time or consistently for any period of time, or that the fund's predicted tracking error and actual tracking error will be similar. The fund's strategy to target a predicted tracking error of approximately 3% compared to the Russell 2000® Index and to blend fundamental and quantitative research may not produce the intended results. In addition, MFS' fundamental research is not available for all issuers. Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to countries with developing economies or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market. REITs Risk: The risks of investing in REITs include certain risks associated with the direct ownership of real estate and the real estate industry in general. These include risks related to general, regional and local economic conditions; difficulties in valuing and disposing of real estate; fluctuations in interest rates and property tax rates; shifts in zoning laws, environmental regulations and other governmental action; cash flow dependency; increased operating expenses; lack of availability of mortgage funds; losses due to natural disasters; overbuilding; losses due to casualty or condemnation; changes in property values and rental rates; the management skill and creditworthiness of the REIT manager; and other factors. The securities of smaller real estate-related issuers can be more volatile and less liquid than securities of larger issuers and their issuers can have more limited financial resources. Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries, and regions to which the fund is exposed. Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs. Large Shareholder Risk: From time to time, shareholders of the fund (which may include institutional investors, financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund shares. These transactions may cause the fund to sell securities or invest additional cash, as the case may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance to the extent that it takes time to invest new cash and the fund maintains a larger cash position than it ordinarily would. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests.The fund’s past performance does not necessarily indicate how the fund will perform in the future. Updated performance is available at mfs.com or by calling 1-877-411-3325. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, they would reduce the returns shown. The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests. The fund’s past performance does not necessarily indicate how the fund will perform in the future. mfs.com 1-877-411-3325 Initial Class Bar Chart. The total return for the three-month period ended March 31, 2025, was (9.98)%. During the period(s) shown in the bar chart, the highest quarterly return was 23.70% (for the calendar quarter ended December 31, 2020) and the lowest quarterly return was (33.45)% (for the calendar quarter ended March 31, 2020). The total return for the three-month period ended 2025-03-31 highest quarterly return 0.2370 2020-12-31 lowest quarterly return -0.3345 2020-03-31 Performance Table. Average Annual Total Returns (For the Periods Ended December 31, 2024) 0.0495 0.0620 0.0803 0.0465 0.0594 0.0775 Reflects no deduction for fees, expenses, or taxes Reflects no deduction for fees, expenses, or taxes Russell 3000® Index 0.2381 0.1386 0.1255 Russell 2000® Index 0.1154 0.0740 0.0782 MFS® Global Real Estate Portfolio Summary of Key Information N/A N/A Investment Objective The fund’s investment objective is to seek total return. Fees and Expenses This table describes the fees and expenses that you may pay when you hold shares of the fund. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which the fund is offered were included, your expenses would be higher. Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): 0.0090 0.0090 0 0.0025 0.0013 0.0013 0.0103 0.0128 -0.0013 -0.0013 0.0090 0.0115 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. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, your expenses would be higher.The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods; your investment has a 5% return each year; and the fund’s operating expenses remain the same. Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 92 315 556 1248 117 393 690 1534 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. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 42% of the average value of its portfolio. 0.42 Principal Investment Strategies MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests at least 80% of the fund’s net assets in U.S. and foreign real estate-related investments. MFS normally invests the fund’s assets primarily in equity securities. MFS generally focuses the fund’s investments in equity real estate investment trusts (REITs) as well as similar entities formed under the laws of non-U.S. countries, but may also invest the fund’s assets in mortgage REITs, hybrid REITs and other U.S. and foreign real estate-related investments, including emerging market real estate-related investments. MFS may invest the fund’s assets in real estate-related investments of any size. However, issuers of real estate-related investments tend to have small-to-medium market capitalizations.MFS normally allocates the fund’s investments across different REIT managers and property types, but may from time to time focus the fund’s investments in any one or a few of these areas.MFS normally invests the fund's assets across different countries and regions, but MFS may invest a significant percentage of the fund's assets in issuers in a single country or region.MFS generally invests the fund's assets in at least three different countries and invests a percentage of the fund's net assets in securities of foreign issuers equal to at least the lesser of 40% or the percentage of foreign issuers in the FTSE EPRA Nareit Developed Real Estate Index less 15%.MFS may invest a significant percentage of the fund’s assets in a single issuer or a small number of issuers.MFS uses an active bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual issuers. For purposes of the fund's 80% policy, net assets include the amount of any borrowings for investment purposes. Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.The principal risks of investing in the fund are: Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Real Estate-Related Investment Risk: The fund’s performance will be closely tied to the performance of real estate-related investments and as a result, can be more volatile than the performance of more broadly-diversified funds. The risks of investing in real estate-related investments include certain risks associated with the direct ownership of real estate and the real estate industry in general. These include risks related to general, regional and local economic conditions; difficulties in valuing and disposing of real estate; fluctuations in interest rates and property tax rates; shifts in zoning laws, environmental regulations and other governmental action; cash flow dependency; increased operating expenses; lack of availability of mortgage funds; losses due to natural disasters; overbuilding; losses due to casualty or condemnation; changes in property values and rental rates; the management skill and creditworthiness of the REIT manager; and other factors. Investment Selection Risk: MFS' investment analysis and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. In addition, to the extent MFS considers quantitative tools in managing the fund, such tools may not produce the intended results. Equity Market Risk/Company Risk: Equity markets are volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the equity markets in general. Certain events can have a dramatic adverse effect on equity markets and may lead to periods of high volatility in an equity market or a segment of an equity market. The value of an investment held by the fund may decline due to factors directly related to the issuer. Small to Medium Cap Risk: The securities of real estate-related issuers that have small to medium market capitalizations can be more volatile and less liquid than securities of larger issuers and such issuers can have more limited financial resources. Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to emerging markets or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market. Emerging Markets Risk: Investments tied economically to emerging markets, especially frontier markets, can involve additional and greater risks than the risks associated with investments in developed markets. Emerging markets can have less developed markets, greater custody and operational risk, less developed legal, regulatory, and accounting systems, greater government involvement in the economy, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater political, social, geopolitical, and economic instability than developed markets. Currency Risk: The value of foreign currencies relative to the U.S. dollar fluctuates in response to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions, and changes in currency exchange rates impact the financial condition of companies or other issuers and may change the value in U.S. dollars of investments denominated in foreign currencies. Focus Risk: Issuers in a single country or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the countries and regions to which the fund is exposed. If MFS invests a significant percentage of the fund's assets in a single issuer or small number of issuers, the fund’s performance could be more volatile than the performance of more diversified funds. Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs. Large Shareholder Risk: From time to time, shareholders of the fund (which may include institutional investors, financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund shares. These transactions may cause the fund to sell securities or invest additional cash, as the case may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance to the extent that it takes time to invest new cash and the fund maintains a larger cash position than it ordinarily would. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests.The fund’s past performance does not necessarily indicate how the fund will perform in the future. Updated performance is available at mfs.com or by calling 1-877-411-3325. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, they would reduce the returns shown. The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests. The fund’s past performance does not necessarily indicate how the fund will perform in the future. mfs.com 1-877-411-3325 Initial Class Bar Chart. The total return for the three-month period ended March 31, 2025, was (0.88)%. During the period(s) shown in the bar chart, the highest quarterly return was 16.58% (for the calendar quarter ended December 31, 2023) and the lowest quarterly return was (23.07)% (for the calendar quarter ended March 31, 2020). The total return for the three-month period ended 2025-03-31 highest quarterly return 0.1658 2023-12-31 lowest quarterly return -0.2307 2020-03-31 Performance Table. Average Annual Total Returns (For the Periods Ended December 31, 2024) -0.0269 0.0091 0.0472 -0.0292 0.0066 0.0447 Reflects no deduction for fees, expenses, or taxes Reflects no deduction for fees, expenses, or taxes MSCI All Country World Index (net div) 0.1749 0.1006 0.0923 FTSE EPRA Nareit Developed Real Estate Index (net div) 0.0094 -0.0100 0.0223 485BPOS 2025-04-30 2024-12-31 0001065698 2025-04-29 false ~ http://www.MFS.com/20241231/role/RRSchedule4 ~ ~ http://www.MFS.com/20241231/role/RRSchedule5 ~ ~ http://www.MFS.com/20241231/role/RRBarChart6 ~ ~ http://www.MFS.com/20241231/role/RRSchedule7 ~ ~ http://www.MFS.com/20241231/role/RRSchedule11 ~ ~ http://www.MFS.com/20241231/role/RRSchedule12 ~ ~ http://www.MFS.com/20241231/role/RRBarChart13 ~ ~ http://www.MFS.com/20241231/role/RRSchedule14 ~ ~ http://www.MFS.com/20241231/role/RRSchedule18 ~ ~ http://www.MFS.com/20241231/role/RRSchedule19 ~ ~ http://www.MFS.com/20241231/role/RRBarChart20 ~ ~ http://www.MFS.com/20241231/role/RRSchedule21 ~ ~ http://www.MFS.com/20241231/role/RRSchedule25 ~ ~ http://www.MFS.com/20241231/role/RRSchedule26 ~ ~ http://www.MFS.com/20241231/role/RRBarChart27 ~ ~ http://www.MFS.com/20241231/role/RRSchedule28 ~ ~ http://www.MFS.com/20241231/role/RRSchedule32 ~ ~ http://www.MFS.com/20241231/role/RRSchedule33 ~ ~ http://www.MFS.com/20241231/role/RRBarChart34 ~ ~ http://www.MFS.com/20241231/role/RRSchedule35 ~ ~ http://www.MFS.com/20241231/role/RRSchedule39 ~ ~ http://www.MFS.com/20241231/role/RRSchedule40 ~ ~ http://www.MFS.com/20241231/role/RRBarChart41 ~ ~ http://www.MFS.com/20241231/role/RRSchedule42 ~ ~ http://www.MFS.com/20241231/role/RRSchedule46 ~ ~ http://www.MFS.com/20241231/role/RRSchedule47 ~ ~ http://www.MFS.com/20241231/role/RRBarChart48 ~ ~ http://www.MFS.com/20241231/role/RRSchedule49 ~ ~ http://www.MFS.com/20241231/role/RRSchedule53 ~ ~ http://www.MFS.com/20241231/role/RRSchedule54 ~ ~ http://www.MFS.com/20241231/role/RRBarChart55 ~ ~ http://www.MFS.com/20241231/role/RRSchedule56 ~ ~ http://www.MFS.com/20241231/role/RRSchedule60 ~ ~ http://www.MFS.com/20241231/role/RRSchedule61 ~ ~ http://www.MFS.com/20241231/role/RRBarChart62 ~ ~ http://www.MFS.com/20241231/role/RRSchedule63 ~ -0.0266 0.2717 0.1524 -0.1078 0.3365 0.0419 0.3405 -0.1096 0.1146 0.0952 -0.0019 0.0503 0.1148 -0.0273 0.1687 0.1231 0.07 -0.1539 0.1042 0.0586 0.0053 0.0715 0.1986 -0.052 0.2696 0.158 0.1576 -0.1827 0.1529 0.1034 0.0035 0.0616 0.1552 -0.0385 0.2223 0.1429 0.1161 -0.1676 0.1299 0.0831 -0.0233 0.1598 0.1367 -0.1145 0.3112 0.0387 0.3099 -0.0879 0.1273 0.1375 -0.0504 0.0257 0.0832 -0.0447 0.0826 0.1355 0.0163 -0.2155 0.0274 -0.0394 0.0048 0.0168 0.0173 0.0128 0.0519 0.0434 0.0016 -0.0414 0.0608 0.053 -0.0415 0.209 0.1497 -0.0511 0.2678 0.0223 0.2964 -0.1837 0.1896 0.0495 0.0074 0.0794 0.1333 -0.0303 0.2687 0.0149 0.3012 -0.2694 0.1146 -0.0269 April 30, 2026 April 30, 2026 April 30, 2026 April 30, 2026 April 30, 2026 April 30, 2026 April 30, 2026 April 30, 2026 April 30, 2026 April 30, 2026 April 30, 2026 April 30, 2026 ~ http://www.MFS.com/20241231/role/RRSchedule8 ~ ~ http://www.MFS.com/20241231/role/RRSchedule15 ~ ~ http://www.MFS.com/20241231/role/RRSchedule22 ~ ~ http://www.MFS.com/20241231/role/RRSchedule29 ~ ~ http://www.MFS.com/20241231/role/RRSchedule36 ~ ~ http://www.MFS.com/20241231/role/RRSchedule43 ~ ~ http://www.MFS.com/20241231/role/RRSchedule50 ~ ~ http://www.MFS.com/20241231/role/RRSchedule57 ~ ~ http://www.MFS.com/20241231/role/RRSchedule64 ~ Massachusetts Financial Services Company (MFS) has agreed in writing to waive at least 0.01% of the fund's management fee as part of an agreement pursuant to which MFS has agreed to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund's Board of Trustees. The agreement to waive at least 0.01% of the management fee will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least April 30, 2026. MFS has agreed in writing to bear the fund’s expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, certain tax reclaim recovery expenses (including contingency fees and closing agreement expenses), and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund's investment activity), such that “Total Annual Fund Operating Expenses” do not exceed 0.88% of the class' average daily net assets annually for Initial Class shares and 1.13% of the class' average daily net assets annually for Service Class shares. This written agreement will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least April 30, 2026. Massachusetts Financial Services Company (MFS) has agreed in writing to waive at least 0.01% of the fund's management fee as part of an agreement pursuant to which MFS has agreed to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund's Board of Trustees. The agreement to waive at least 0.01% of the management fee will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least April 30, 2026. Massachusetts Financial Services Company (MFS) has agreed in writing to waive at least 0.01% of the fund's management fee as part of an agreement pursuant to which MFS has agreed to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund's Board of Trustees. The agreement to waive at least 0.01% of the management fee will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least April 30, 2026. Massachusetts Financial Services Company (MFS) has agreed in writing to waive at least 0.01% of the fund's management fee as part of an agreement pursuant to which MFS has agreed to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund's Board of Trustees. The agreement to waive at least 0.01% of the management fee will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least April 30, 2026. Massachusetts Financial Services Company (MFS) has agreed in writing to waive at least 0.01% of the fund's management fee as part of an agreement pursuant to which MFS has agreed to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund's Board of Trustees. The agreement to waive at least 0.01% of the management fee will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least April 30, 2026. Massachusetts Financial Services Company (MFS) has agreed in writing to waive at least 0.01% of the fund's management fee as part of an agreement pursuant to which MFS has agreed to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund's Board of Trustees. The agreement to waive at least 0.01% of the management fee will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least April 30, 2026. MFS has agreed in writing to bear the fund’s expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, certain tax reclaim recovery expenses (including contingency fees and closing agreement expenses), and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund's investment activity), such that “Total Annual Fund Operating Expenses” do not exceed 0.90% of the class' average daily net assets annually for Initial Class shares and 1.15% of the class' average daily net assets annually for Service Class shares. This written agreement will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least April 30, 2026.