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cik0000356349:Russell3000Index35Member 2025-01-01 2025-12-31 0000356349 cik0000356349:S000032712Member cik0000356349:Russell3000Index35Member 2021-01-01 2025-12-31 0000356349 cik0000356349:S000032712Member cik0000356349:Russell3000Index35Member 2016-01-01 2025-12-31 0000356349 cik0000356349:S000032712Member cik0000356349:Russell2000ValueIndex36Member 2026-02-28 2026-02-28 0000356349 cik0000356349:S000032712Member cik0000356349:Russell2000ValueIndex36Member 2025-01-01 2025-12-31 0000356349 cik0000356349:S000032712Member cik0000356349:Russell2000ValueIndex36Member 2021-01-01 2025-12-31 0000356349 cik0000356349:S000032712Member cik0000356349:Russell2000ValueIndex36Member 2016-01-01 2025-12-31 iso4217:USD pure N-1A MFS® SERIES TRUST XIII 2026-06-26 2026-06-26 MFS® Diversified Income Fund Summary of Key Information DIFAX DIFCX DIFIX DIFDX DIFEX DIFFX DIFGX DIFHX Investment Objective The fund’s investment objective is to seek total return 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 buy, hold, and sell shares of the fund. Investors may also pay commissions or other fees to their financial intermediaries when they buy, hold, and sell shares of the fund, which are not reflected below. You may qualify for sales charge reductions if, with respect to Class A shares, you and certain members of your family invest, or agree to invest in the future, at least $100,000 in MFS funds. More information about these and other waivers and reductions is available from your financial intermediary and in “Sales Charges and Waivers and Reductions” on page 15 and “Appendix A – Waivers and Reductions of Sales Charges” on page A-1 of the fund’s prospectus. You may qualify for sales charge reductions if, with respect to Class A shares, you and certain members of your family invest, or agree to invest in the future, at least $100,000 in MFS funds. 100000 Shareholder Fees (fees paid directly from your investment): 0.0425 0 0 0 0 0 0 0 0.0100 0.0100 0 0 0 0 0 0 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 0.0025 0.0100 0 0.0100 0.0050 0.0025 0 0 0.0015 0.0015 0.0015 0.0015 0.0015 0.0015 0.0015 0.0006 0.0095 0.0170 0.0070 0.0170 0.0120 0.0095 0.0070 0.0061 -0.0006 -0.0006 -0.0006 -0.0006 -0.0006 -0.0006 -0.0006 -0.0006 0.0089 0.0164 0.0064 0.0164 0.0114 0.0089 0.0064 0.0055 Example This example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods (unless otherwise indicated); 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: 512 709 923 1537 267 530 917 1804 167 530 917 1804 65 218 384 865 167 530 917 2004 116 375 654 1449 91 297 520 1161 65 218 384 865 56 189 334 756 Portfolio Turnover The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. 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 the fund’s assets primarily in a broad range of debt instruments and equity securities of U.S. and foreign issuers, including real estate-related investments and emerging market securities. MFS allocates the fund’s assets across the following categories based on its interpretation of economic and money market conditions, fiscal and monetary policy and asset class and/or security values. When MFS' assessment of the relative attractiveness of these categories is neutral, the fund's exposure to these categories is expected to be approximately:<table cellpadding="0" cellspacing="0" style="border-collapse:collapse" width="100%"><tr style="font-size:1pt;"><td style="width:61.13%;"> </td><td style="width:38.87%;"> </td></tr><tr><td style="vertical-align:top; 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;">Category</td><td style="vertical-align:top; 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;">Neutral Position</td></tr><tr><td style="vertical-align:top; 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;">Investment Grade Quality Debt Instruments</td><td style="vertical-align:top; 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;">15%</td></tr><tr><td style="vertical-align:top; 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;">Lower Quality Debt Instruments</td><td style="vertical-align:top; 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;">25%</td></tr><tr><td style="vertical-align:top; 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. Government Securities</td><td style="vertical-align:top; 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;">10%</td></tr><tr><td style="vertical-align:top; 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;">Emerging Market Debt Instruments</td><td style="vertical-align:top; 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;">15%</td></tr><tr><td style="vertical-align:top; 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;">Dividend-Paying Equity Securities</td><td style="vertical-align:top; 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><tr><td style="vertical-align:top; 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;">Real Estate-Related Investments</td><td style="vertical-align:top; 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;">15%</td></tr></table>These allocations may vary significantly from time to time.For the debt instrument portion of the fund, MFS normally focuses on investing the fund's assets in investment grade quality corporate debt instruments, U.S. Government securities, below investment grade quality debt instruments of developed market issuers, and debt instruments of emerging market issuers (including below investment grade quality debt instruments of emerging market issuers). Of the fund’s investments in debt instruments, MFS may invest up to 100% of these investments in below investment grade quality debt instruments. MFS may purchase or sell securities for the fund on a when-issued, delayed delivery, or forward commitment basis where payment and delivery take place at a future settlement date, including mortgage-backed securities purchased or sold in the to be announced (TBA) market. For the equity portion of the fund, MFS focuses on investing the fund’s assets in dividend-paying stocks of U.S. and foreign issuers. In selecting equity 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. While MFS may invest the equity portion of the fund’s assets in securities of companies of any size, MFS primarily invests in securities of companies with large capitalizations.For the real estate-related portion of the fund, MFS invests the fund’s assets in real estate investment trusts (REITs) and other companies principally engaged in the real estate industry. MFS generally focuses the fund’s real estate-related investments in equity REITs, but may also invest the fund’s assets in mortgage REITs and other real estate-related investments. Issuers of real estate-related investments tend to have small-to-medium market capitalizations.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. 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 uses an active bottom-up investment approach to buying and selling investments for the fund. For the debt and real estate-related portions of the fund, investments are selected primarily based on fundamental analysis of individual issuers and instruments. For the equity portion of the fund, investments are selected primarily based on blending fundamental and quantitative research and then constructing a portfolio of equity securities while managing various risk factors (e.g., issuer, industry, and sector weightings, market capitalization, and volatility). Quantitative models that systematically evaluate issuers and instruments are used by the fund's equity securities portfolio manager and may also be considered by the fund's other portfolio managers.MFS may invest the fund's assets in other mutual funds advised by MFS that invest in particular investment types rather than invest directly in such investments. 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: 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 the resulting allocation among asset classes 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. 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. 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. 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. Furthermore, investments in particular industries, sectors, countries, or regions may be more volatile than the broader market as a whole. 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. 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. 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. 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 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. 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 funds invests.Performance information prior to June 15, 2021, reflects time periods when the fund did not have an investment strategy of allocating a portion of its assets to investment grade quality debt instruments. The fund's investment strategies changed effective June 15, 2021. The fund’s past performance (before and after taxes) does not necessarily indicate how the fund will perform in the future. Updated performance is available online at mfs.com or by calling 1-800-225-2606. 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 funds invests. The fund’s past performance (before and after taxes) does not necessarily indicate how the fund will perform in the future. mfs.com 1-800-225-2606 Class A Bar Chart. The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund’s shares. If these sales charges were included, they would reduce the returns shown. The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund’s shares. If these sales charges were included, they would reduce the returns shown. The total return for the three-month period ended March 31, 2026, was 1.26%. During the period(s) shown in the bar chart, the highest quarterly return was 8.65% (for the calendar quarter ended December 31, 2023) and the lowest quarterly return was (13.45)% (for the calendar quarter ended March 31, 2020). The total return for the three-month period ended 2026-03-31 0.0126 highest quarterly return 0.0865 2023-12-31 lowest quarterly return -0.1345 2020-03-31 Performance Table. Average Annual Total Returns (For the Periods Ended December 31, 2025) Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes 0.0762 0.0285 0.0436 0.0970 0.0387 0.0524 0.0863 0.0285 0.0420 0.0916 0.0337 0.0472 0.0943 0.0362 0.0498 0.0961 0.0387 0.0524 0.0971 0.0396 0.0533 0.0470 0.0271 0.0452 Returns After Taxes on Distributions 0.0253 0.0108 0.0305 Returns After Taxes on Distributions and Sale of Fund Shares 0.0285 0.0147 0.0295 Reflects no deduction for fees, expenses, or taxes Reflects no deduction for fees, expenses, or taxes Standard & Poor's 500 Stock Index 0.1788 0.1442 0.1482 MFS Diversified Income Fund Blended Index 0.1053 0.0402 0.0562 As of December 31, 2025, the MFS Diversified Income Fund Blended Index (the Blended Index) consisted of the following indices and weightings: 15% MSCI US REIT Index; 15% JPMorgan Emerging Markets Bond Index Global Diversified; 10% Bloomberg U.S. Government/Mortgage Index; 25% Bloomberg U.S. Corporate High-Yield 2% Issuer Capped Index; 20% MSCI All Country World (ACWI) High Dividend Yield Index; and 15% Bloomberg U.S. Credit Index. The components and weightings of the Blended Index may have differed during the periods, and may differ in the future.After-tax returns are calculated using the historical highest individual U.S. federal marginal income tax rates and do not reflect the impact of state and local taxes. Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (IRAs). The after-tax returns are shown for only one of the fund’s classes of shares, and after-tax returns for the fund’s other classes of shares will vary from the returns shown. As of December 31, 2025, the MFS Diversified Income Fund Blended Index (the Blended Index) consisted of the following indices and weightings: 15% MSCI US REIT Index; 15% JPMorgan Emerging Markets Bond Index Global Diversified; 10% Bloomberg U.S. Government/Mortgage Index; 25% Bloomberg U.S. Corporate High-Yield 2% Issuer Capped Index; 20% MSCI All Country World (ACWI) High Dividend Yield Index; and 15% Bloomberg U.S. Credit Index. The components and weightings of the Blended Index may have differed during the periods, and may differ in the future. Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (IRAs). The after-tax returns are shown for only one of the fund’s classes of shares, and after-tax returns for the fund’s other classes of shares will vary from the returns shown. MFS® Government Securities Fund Summary of Key Information MFGSX MFGBX MFGDX MGSIX MFGGX MGVSX MFGHX MFGJX MFGKX Investment Objective The fund’s investment objective is to seek total return 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 buy, hold, and sell shares of the fund. Investors may also pay commissions or other fees to their financial intermediaries when they buy, hold, and sell shares of the fund, which are not reflected below. You may qualify for sales charge reductions if, with respect to Class A shares, you and certain members of your family invest, or agree to invest in the future, at least $100,000 in MFS funds. More information about these and other waivers and reductions is available from your financial intermediary and in “Sales Charges and Waivers and Reductions” on page 12 and “Appendix A – Waivers and Reductions of Sales Charges” on page A-1 of the fund’s prospectus. You may qualify for sales charge reductions if, with respect to Class A shares, you and certain members of your family invest, or agree to invest in the future, at least $100,000 in MFS funds. 100000 Shareholder Fees (fees paid directly from your investment): 0.0425 0 0 0 0 0 0 0 0 0.0100 0.0400 0.0100 0 0 0 0 0 0 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): 0.0038 0.0038 0.0038 0.0038 0.0038 0.0038 0.0038 0.0038 0.0038 0.0025 0.0100 0.0100 0 0.0100 0.0050 0.0025 0 0 0.0015 0.0015 0.0015 0.0015 0.0015 0.0015 0.0015 0.0015 0.0006 0.0078 0.0153 0.0153 0.0053 0.0153 0.0103 0.0078 0.0053 0.0044 -0.0001 -0.0001 -0.0001 -0.0001 -0.0001 -0.0001 -0.0001 -0.0001 -0.0001 0.0077 0.0152 0.0152 0.0052 0.0152 0.0102 0.0077 0.0052 0.0043 Example This example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods (unless otherwise indicated); 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: 500 663 839 1349 555 782 1033 1620 155 482 833 1620 255 482 833 1620 155 482 833 1620 53 169 295 664 155 482 833 1823 104 327 568 1259 79 248 432 965 53 169 295 664 44 140 245 554 Portfolio Turnover The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. 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 139% of the average value of its portfolio (53% excluding to be announced (TBA) transactions). 1.39 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. Government securities. U.S. Government securities are securities issued or guaranteed by the U.S. Treasury, by an agency or instrumentality of the U.S. Government, or by a U.S. Government-sponsored entity, including mortgage-backed securities and other types of securitized instruments issued or guaranteed by such entities. MFS may also invest the fund's assets in other debt instruments. MFS generally invests substantially all of the fund’s assets in investment grade quality debt instruments.MFS may purchase or sell securities for the fund on a when-issued, delayed delivery, or forward commitment basis where payment and delivery take place at a future settlement date, including mortgage-backed securities purchased or sold in the TBA market. MFS may invest the fund’s assets in foreign securities. MFS may invest a significant percentage of the fund’s assets in a single issuer or a small number of issuers.MFS may engage in active and frequent trading in pursuing the fund’s principal investment strategies.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 uses an active investment approach in managing the fund that combines top-down considerations and bottom-up fundamental investment analysis to make decisions about sector allocations, duration and yield curve positioning, and security selection. In addition, market technicals (e.g., bond supply and demand dynamics) are typically considered in determining sector allocations and specific security selection. Quantitative screening tools may also be considered in determining the fund’s portfolio positioning.For purposes of the fund's 80% policy, net assets include the amount of any borrowings for investment purposes. MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests at least 80% of the fund’s net assets in U.S. Government securities. U.S. Government securities are securities issued or guaranteed by the U.S. Treasury, by an agency or instrumentality of the U.S. Government, or by a U.S. Government-sponsored entity, including mortgage-backed securities and other types of securitized instruments issued or guaranteed by such entities. 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: 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.U.S. Government securities not supported as to the payment of principal or interest by the U.S. Treasury are subject to greater credit risk than are U.S. Government securities supported by the U.S. Treasury. 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. In addition, inflation-adjusted debt instruments may lose value in the event the actual rate of inflation is different than the rate of the applicable inflation index. 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 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 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. Furthermore, investments in particular countries or regions may be more volatile than the broader market as a whole. 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. 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. TBA transactions may significantly increase the fund's portfolio turnover rate. Active and Frequent Trading Risk: Frequent trading may increase transaction costs, which can reduce the fund's return, and can also increase the possibility of capital gain and ordinary distributions. Frequent trading can also result in the realization of a higher percentage of short-term capital gains and a lower percentage of long-term capital gains as compared to a fund that trades less frequently, which would generally increase your tax liability unless you hold your shares through a tax-advantaged or tax-exempt vehicle. 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 (before and after taxes) does not necessarily indicate how the fund will perform in the future. Updated performance is available online at mfs.com or by calling 1-800-225-2606. 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 (before and after taxes) does not necessarily indicate how the fund will perform in the future. mfs.com 1-800-225-2606 Class A Bar Chart. The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund’s shares. If these sales charges were included, they would reduce the returns shown. The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund’s shares. If these sales charges were included, they would reduce the returns shown. The total return for the three-month period ended March 31, 2026, was (0.18)%. During the period(s) shown in the bar chart, the highest quarterly return was 6.23% (for the calendar quarter ended December 31, 2023) and the lowest quarterly return was (4.85)% (for the calendar quarter ended September 30, 2022). The total return for the three-month period ended 2026-03-31 -0.0018 highest quarterly return 0.0623 2023-12-31 lowest quarterly return -0.0485 2022-09-30 Performance Table. Average Annual Total Returns (For the Periods Ended December 31, 2025) Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes 0.0182 -0.0203 0.0042 0.0493 -0.0166 0.0042 0.0700 -0.0068 0.0126 0.0594 -0.0165 0.0028 0.0635 -0.0118 0.0076 0.0673 -0.0092 0.0102 0.0687 -0.0068 0.0127 0.0697 -0.0058 0.0137 0.0208 -0.0178 0.0058 Returns After Taxes on Distributions 0.0063 -0.0280 -0.0040 Returns After Taxes on Distributions and Sale of Fund Shares 0.0121 -0.0178 0.0001 Reflects no deduction for fees, expenses, or taxes Reflects no deduction for fees, expenses, or taxes Bloomberg U.S. Aggregate Bond Index 0.0730 -0.0036 0.0201 Bloomberg U.S. Government/Mortgage Index 0.0709 -0.0053 0.0146 After-tax returns are calculated using the historical highest individual U.S. federal marginal income tax rates and do not reflect the impact of state and local taxes. Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (IRAs). The after-tax returns are shown for only one of the fund’s classes of shares, and after-tax returns for the fund’s other classes of shares will vary from the returns shown. Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (IRAs). The after-tax returns are shown for only one of the fund’s classes of shares, and after-tax returns for the fund’s other classes of shares will vary from the returns shown. MFS® New Discovery Value Fund Summary of Key Information NDVAX NDVBX NDVCX NDVIX NDVRX NDVSX NDVTX NDVUX NDVVX 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 buy, hold, and sell shares of the fund. Investors may also pay commissions or other fees to their financial intermediaries when they buy, hold, and sell shares of the fund, which are not reflected below. You may qualify for sales charge reductions if, with respect to Class A shares, you and certain members of your family invest, or agree to invest in the future, at least $50,000 in MFS funds. More information about these and other waivers and reductions is available from your financial intermediary and in “Sales Charges and Waivers and Reductions” on page 11 and “Appendix A – Waivers and Reductions of Sales Charges” on page A-1 of the fund’s prospectus. You may qualify for sales charge reductions if, with respect to Class A shares, you and certain members of your family invest, or agree to invest in the future, at least $50,000 in MFS funds. 50000 Shareholder Fees (fees paid directly from your investment): 0.0575 0 0 0 0 0 0 0 0 0.0100 0.0400 0.0100 0 0 0 0 0 0 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): 0.0083 0.0083 0.0083 0.0083 0.0083 0.0083 0.0083 0.0083 0.0083 0.0025 0.0100 0.0100 0 0.0100 0.0050 0.0025 0 0 0.0015 0.0015 0.0015 0.0015 0.0015 0.0015 0.0015 0.0015 0.0005 0.0123 0.0198 0.0198 0.0098 0.0198 0.0148 0.0123 0.0098 0.0088 -0.0001 -0.0001 -0.0001 -0.0001 -0.0001 -0.0001 -0.0001 -0.0001 -0.0001 0.0122 0.0197 0.0197 0.0097 0.0197 0.0147 0.0122 0.0097 0.0087 Example This example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods (unless otherwise indicated); 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: 692 942 1211 1977 600 920 1267 2112 200 620 1067 2112 300 620 1067 2112 200 620 1067 2112 99 311 541 1200 200 620 1067 2305 150 467 807 1768 124 389 675 1488 99 311 541 1200 89 280 487 1083 Portfolio Turnover The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. 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 47% of the average value of its portfolio. 0.47 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 value companies. Value companies are companies that MFS believes are undervalued compared to their perceived worth in the marketplace. MFS considers a number of factors when determining whether a company is undervalued, including whether (i) the issuer is included in an index which is representative of value companies; (ii) the issuer is classified as a value company by an independent third party financial data provider and/or (iii) the issuer exhibits the characteristics of a value company, considering metrics such as historical and/or projected price-to-book, price-to-earnings, and price-to-cash flow ratios, enterprise value (the total value of the issuer’s outstanding equity and debt) relative to earnings, and free cash flow yield compared to the applicable equity market and/or to issuers in the same sector or industry. In assessing the relative value of an issuer, MFS may also consider measures of financial quality, such as indicators of profitability (i.e., return on equity and return on invested capital), balance sheet strength (including leverage and interest coverage ratios), and capital allocation discipline. Value companies tend to have stock prices that are low relative to their earnings, dividends, assets, or other financial measures.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.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.For purposes of the fund's 80% policy, net assets include the amount of any borrowings for investment purposes. MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests at least 80% of the fund’s net assets in value companies. Value companies are companies that MFS believes are undervalued compared to their perceived worth in the marketplace. MFS considers a number of factors when determining whether a company is undervalued, including whether (i) the issuer is included in an index which is representative of value companies; (ii) the issuer is classified as a value company by an independent third party financial data provider and/or (iii) the issuer exhibits the characteristics of a value company, considering metrics such as historical and/or projected price-to-book, price-to-earnings, and price-to-cash flow ratios, enterprise value (the total value of the issuer’s outstanding equity and debt) relative to earnings, and free cash flow yield compared to the applicable equity market and/or to issuers in the same sector or industry. In assessing the relative value of an issuer, MFS may also consider measures of financial quality, such as indicators of profitability (i.e., return on equity and return on invested capital), balance sheet strength (including leverage and interest coverage ratios), and capital allocation discipline. Value companies tend to have stock prices that are low relative to their earnings, dividends, assets, or other financial measures. 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: 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. Furthermore, investments in particular industries, sectors, countries, or regions may be more volatile than the broader market as a whole. 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 (before and after taxes) does not necessarily indicate how the fund will perform in the future. Updated performance is available online at mfs.com or by calling 1-800-225-2606. 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 (before and after taxes) does not necessarily indicate how the fund will perform in the future. mfs.com 1-800-225-2606 Class A Bar Chart. The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund’s shares. If these sales charges were included, they would reduce the returns shown. The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund’s shares. If these sales charges were included, they would reduce the returns shown. The total return for the three-month period ended March 31, 2026, was 1.38%. During the period(s) shown in the bar chart, the highest quarterly return was 30.96% (for the calendar quarter ended December 31, 2020) and the lowest quarterly return was (34.36)% (for the calendar quarter ended March 31, 2020). The total return for the three-month period ended 2026-03-31 0.0138 highest quarterly return 0.3096 2020-12-31 lowest quarterly return -0.3436 2020-03-31 Performance Table. Average Annual Total Returns (For the Periods Ended December 31, 2025) Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes -0.0225 0.0688 0.0934 0.0046 0.0716 0.0934 0.0241 0.0824 0.1027 0.0142 0.0718 0.0918 0.0193 0.0770 0.0973 0.0219 0.0798 0.1000 0.0242 0.0825 0.1028 0.0252 0.0836 0.1039 -0.0369 0.0671 0.0935 Returns After Taxes on Distributions -0.0618 0.0455 0.0750 Returns After Taxes on Distributions and Sale of Fund Shares -0.0083 0.0490 0.0713 Reflects no deduction for fees, expenses, or taxes Reflects no deduction for fees, expenses, or taxes Russell 3000® Index 0.1715 0.1315 0.1429 Russell 2000® Value Index 0.1259 0.0888 0.0927 After-tax returns are calculated using the historical highest individual U.S. federal marginal income tax rates and do not reflect the impact of state and local taxes. Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (IRAs). The after-tax returns are shown for only one of the fund’s classes of shares, and after-tax returns for the fund’s other classes of shares will vary from the returns shown. Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (IRAs). The after-tax returns are shown for only one of the fund’s classes of shares, and after-tax returns for the fund’s other classes of shares will vary from the returns shown. 485BPOS 2026-06-26 2026-02-28 0000356349 2026-06-25 false ~ http://xbrl.sec.gov/rr/role/ShareholderFeesData row dei_DocumentInformationDocumentAxis compact cik0000356349_S000012219Summary1Member row dei_LegalEntityAxis compact cik0000356349_S000012219Member ~ ~ http://xbrl.sec.gov/rr/role/OperatingExpensesData row dei_DocumentInformationDocumentAxis compact cik0000356349_S000012219Summary1Member row dei_LegalEntityAxis compact cik0000356349_S000012219Member ~ ~ http://xbrl.sec.gov/rr/role/ExpenseExample row dei_DocumentInformationDocumentAxis compact cik0000356349_S000012219Summary1Member row dei_LegalEntityAxis compact cik0000356349_S000012219Member ~ ~ http://xbrl.sec.gov/rr/role/ExpenseExampleNoRedemption row dei_DocumentInformationDocumentAxis compact cik0000356349_S000012219Summary1Member row dei_LegalEntityAxis compact cik0000356349_S000012219Member ~ ~ http://xbrl.sec.gov/rr/role/PerformanceTableData column period compact * row dei_DocumentInformationDocumentAxis compact cik0000356349_S000012219Summary1Member row dei_LegalEntityAxis compact cik0000356349_S000012219Member row oef_ClassAxis compact * row oef_PerformanceMeasureAxis compact * ~ ~ http://xbrl.sec.gov/rr/role/ShareholderFeesData row dei_DocumentInformationDocumentAxis compact cik0000356349_S000000693Summary2Member row dei_LegalEntityAxis compact cik0000356349_S000000693Member ~ ~ http://xbrl.sec.gov/rr/role/OperatingExpensesData row dei_DocumentInformationDocumentAxis compact cik0000356349_S000000693Summary2Member row dei_LegalEntityAxis compact cik0000356349_S000000693Member ~ ~ http://xbrl.sec.gov/rr/role/ExpenseExample row dei_DocumentInformationDocumentAxis compact cik0000356349_S000000693Summary2Member row dei_LegalEntityAxis compact cik0000356349_S000000693Member ~ ~ http://xbrl.sec.gov/rr/role/ExpenseExampleNoRedemption row dei_DocumentInformationDocumentAxis compact cik0000356349_S000000693Summary2Member row dei_LegalEntityAxis compact cik0000356349_S000000693Member ~ ~ http://xbrl.sec.gov/rr/role/PerformanceTableData column period compact * row dei_DocumentInformationDocumentAxis compact cik0000356349_S000000693Summary2Member row dei_LegalEntityAxis compact cik0000356349_S000000693Member row oef_ClassAxis compact * row oef_PerformanceMeasureAxis compact * ~ ~ http://xbrl.sec.gov/rr/role/ShareholderFeesData row dei_DocumentInformationDocumentAxis compact cik0000356349_S000032712Summary3Member row dei_LegalEntityAxis compact cik0000356349_S000032712Member ~ ~ http://xbrl.sec.gov/rr/role/OperatingExpensesData row dei_DocumentInformationDocumentAxis compact cik0000356349_S000032712Summary3Member row dei_LegalEntityAxis compact cik0000356349_S000032712Member ~ ~ http://xbrl.sec.gov/rr/role/ExpenseExample row dei_DocumentInformationDocumentAxis compact cik0000356349_S000032712Summary3Member row dei_LegalEntityAxis compact cik0000356349_S000032712Member ~ ~ http://xbrl.sec.gov/rr/role/ExpenseExampleNoRedemption row dei_DocumentInformationDocumentAxis compact cik0000356349_S000032712Summary3Member row dei_LegalEntityAxis compact cik0000356349_S000032712Member ~ ~ http://xbrl.sec.gov/rr/role/PerformanceTableData column period compact * row dei_DocumentInformationDocumentAxis compact cik0000356349_S000032712Summary3Member row dei_LegalEntityAxis compact cik0000356349_S000032712Member row oef_ClassAxis compact * row oef_PerformanceMeasureAxis compact * ~ 0.0849 0.0864 -0.0369 0.1738 0.0215 0.093 -0.1301 0.0923 0.0514 0.0934 0.0052 0.0191 0.0027 0.0619 0.0624 -0.0218 -0.1222 0.0383 0.0044 0.0661 0.2613 0.1465 -0.1134 0.3327 0.034 0.3345 -0.1107 0.1094 0.091 0.0219 This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase. June 30, 2027 June 30, 2027 June 30, 2027 June 30, 2027 June 30, 2027 June 30, 2027 June 30, 2027 June 30, 2027 This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase. June 30, 2027 June 30, 2027 June 30, 2027 June 30, 2027 June 30, 2027 June 30, 2027 June 30, 2027 June 30, 2027 June 30, 2027 This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase. June 30, 2027 June 30, 2027 June 30, 2027 June 30, 2027 June 30, 2027 June 30, 2027 June 30, 2027 June 30, 2027 June 30, 2027 ~ http://www.MFS.com/20260228/role/RRRiskTable3 ~ ~ http://www.MFS.com/20260228/role/RRRiskTable5 ~ ~ http://www.MFS.com/20260228/role/RRRiskTable7 ~ This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase. 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 June 30, 2027. 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 0.89% of the class' average daily net assets annually for each of Class A and Class R3 shares, 1.64% of the class' average daily net assets annually for each of Class C and Class R1 shares, 0.64% of the class' average daily net assets annually for each of Class I and Class R4 shares, 1.14% of the class' average daily net assets annually for Class R2 shares, and 0.55% of the class' average daily net assets annually for Class R6 shares. This written agreement will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least June 30, 2027. Shares automatically convert to Class A shares approximately eight years after purchase; therefore, the expense examples reflect Class A share expenses after eight years. This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase. 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 June 30, 2027. Shares automatically convert to Class A shares approximately eight years after purchase; therefore, the expense examples reflect Class A share expenses after eight years. This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase. 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 June 30, 2027. Shares automatically convert to Class A shares approximately eight years after purchase; therefore, the expense examples reflect Class A share expenses after eight years.