0000819673 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:C000006697Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:C000006699Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:C000006700Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:C000006701Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:C000006703Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:C000006705Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:C000006706Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:C000006698Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:C000126358Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:PrincipalRisksMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member rr:RiskLoseMoneyMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member rr:RiskNotInsuredMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:InvestmentSelectionRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:EquityMarketRiskCompanyRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:GrowthCompanyRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:ForeignRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:EmergingMarketsRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:CurrencyRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:FocusRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:LiquidityRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:LargeShareholderRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member rr:AfterTaxesOnDistributionsMember cik0000819673:C000006697Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member rr:AfterTaxesOnDistributionsAndSalesMember cik0000819673:C000006697Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:MSCIAllCountryWorldIndexnetdiv1Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002490Member cik0000819673:MSCIAllCountryWorldGrowthIndexnetdiv2Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:C000006707Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:C000006708Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:C000006709Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:C000006710Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:C000200511Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:PrincipalRisksMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member rr:RiskLoseMoneyMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member rr:RiskNotInsuredMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:InvestmentSelectionRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:DebtMarketRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:InterestRateRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:CreditRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:ForeignRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:EmergingMarketsRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:CurrencyRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:FocusRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:PrepaymentExtensionRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:When-IssuedDelayedDeliveryandForwardCommitmentTransactionRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:DerivativesRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:LeveragingRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:CounterpartyandThirdPartyRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:LiquidityRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:LargeShareholderRiskMember 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member rr:AfterTaxesOnDistributionsMember cik0000819673:C000006707Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member rr:AfterTaxesOnDistributionsAndSalesMember cik0000819673:C000006707Member 2024-10-31 2024-10-31 0000819673 cik0000819673:S000002491Member cik0000819673:BloombergUSAggregateBondIndex3Member 2024-10-31 2024-10-31 iso4217:USD pure utr:Y N-1A MFS® SERIES TRUST VIII 2025-02-28 2025-02-28 MFS® Global Growth Fund Summary of Key Information MWOFX MWOBX MWOCX MWOIX MWOGX MGWRX MWOHX MWOJX MWOKX 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 10 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): 0.0090 0.0090 0.0090 0.0090 0.0090 0.0090 0.0090 0.0090 0.0090 0.0025 0.0100 0.0100 0 0.0100 0.0050 0.0025 0 0 0.0017 0.0017 0.0017 0.0017 0.0017 0.0017 0.0017 0.0017 0.0009 0.0132 0.0207 0.0207 0.0107 0.0207 0.0157 0.0132 0.0107 0.0099 -0.0010 -0.0010 -0.0010 -0.0010 -0.0010 -0.0010 -0.0010 -0.0010 -0.0009 0.0122 0.0197 0.0197 0.0097 0.0197 0.0147 0.0122 0.0097 0.0090 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: 692 960 1248 2066 600 939 1304 2200 200 639 1104 2200 300 639 1104 2200 200 639 1104 2200 99 330 580 1297 200 639 1104 2392 150 486 846 1859 124 408 714 1582 99 330 580 1297 92 306 538 1205 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 23% of the average value of its portfolio. 0.23 Principal Investment Strategies MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests the fund’s assets primarily in U.S. and foreign equity securities, including emerging market equity securities. Equity securities include common stocks, depositary receipts, 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 to have above average earnings growth potential compared to other companies (growth companies).MFS may invest the fund’s assets in securities of companies of any size. 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 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 MSCI All Country World Growth Index less 15%.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. 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. 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 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) one or more other measures of performance for markets 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) one or more other measures of performance for markets 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. During the period(s) shown in the bar chart, the highest quarterly return was 19.69% (for the calendar quarter ended June 30, 2020) and the lowest quarterly return was (19.00)% (for the calendar quarter ended March 31, 2020). highest quarterly return 0.1969 2020-06-30 lowest quarterly return -0.1900 2020-03-31 Performance Table. Average Annual Total Returns (For the Periods Ended December 31, 2024) 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 0.0586 0.0780 0.0964 0.0886 0.0810 0.0964 0.1096 0.0919 0.1058 0.0987 0.0810 0.0948 0.1040 0.0864 0.1003 0.1068 0.0891 0.1030 0.1095 0.0919 0.1058 0.1105 0.0927 0.1067 0.0431 0.0764 0.0966 Returns After Taxes on Distributions 0.0310 0.0664 0.0870 Returns After Taxes on Distributions and Sale of Fund Shares 0.0342 0.0592 0.0771 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 MSCI All Country World Growth Index (net div) 0.2423 0.1307 0.1188 Effective March 1, 2024, the MSCI All Country World Index (net div) replaced the MSCI All Country World Growth Index (net div) because MFS believes the MSCI All Country World Index (net div) better reflects MFS’ implementation of the fund’s investment strategy. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. 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. Effective March 1, 2024, the MSCI All Country World Index (net div) replaced the MSCI All Country World Growth Index (net div) because MFS believes the MSCI All Country World Index (net div) better reflects MFS’ implementation of the fund’s investment strategy. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. 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® Income Fund Summary of Key Information MFIOX MIOBX MIOCX MFIIX MFIWX Investment Objective The fund’s investment objective is to seek total return with an emphasis on high 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 0.0100 0.0400 0.0100 0 0 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): 0.0044 0.0044 0.0044 0.0044 0.0044 0.0025 0.0100 0.0100 0 0 0.0015 0.0015 0.0015 0.0015 0.0006 0.0084 0.0159 0.0159 0.0059 0.0050 -0.0011 -0.0011 -0.0011 -0.0011 -0.0010 0.0073 0.0148 0.0148 0.0048 0.0040 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: 496 671 861 1408 551 791 1055 1679 151 491 855 1679 251 491 855 1679 151 491 855 1679 49 178 318 727 41 150 270 619 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 50% of the average value of its portfolio. 0.50 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 issued by U.S. and foreign corporate, government, and other entities, including below investment grade quality debt instruments and debt instruments of issuers located in emerging market countries. MFS focuses on investing the fund's assets in corporate bonds, mortgage-backed securities and other securitized instruments (including commercial mortgage-backed securities, collateralized debt obligations, and/or other asset-backed securities), U.S. Government securities, and debt instruments of issuers located in emerging market countries. MFS allocates the fund’s assets across these categories with a view toward broad diversification across and within these categories. MFS normally invests up to 35% of the fund’s assets, at time of purchase, 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. 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 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. 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.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. 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 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. 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 a broad measure of market performance.Performance information prior to December 2, 2019, reflects time periods when the fund had (i) a policy permitting the fund to invest up to 100% of its assets in below investment grade quality debt instruments and (ii) a policy permitting the fund to invest in equity securities as a principal investment strategy. The fund's investment policies and strategies changed effective December 2, 2019. 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 a broad measure of market performance. 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. During the period(s) shown in the bar chart, the highest quarterly return was 8.34% (for the calendar quarter ended June 30, 2020) and the lowest quarterly return was (6.30)% (for the calendar quarter ended June 30, 2022). highest quarterly return 0.0834 2020-06-30 lowest quarterly return -0.0630 2022-06-30 Performance Table. Average Annual Total Returns (For the Periods Ended December 31, 2024) Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes Returns Before Taxes -0.0204 -0.0030 0.0175 0.0088 0.0007 0.0176 0.0289 0.0104 0.0260 0.0299 0.0113 0.0267 -0.0172 -0.0008 0.0191 Returns After Taxes on Distributions -0.0369 -0.0157 0.0043 Returns After Taxes on Distributions and Sale of Fund Shares -0.0103 -0.0066 0.0082 Reflects no deduction for fees, expenses, or taxes Bloomberg U.S. Aggregate Bond Index 0.0125 -0.0033 0.0135 After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. 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. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. 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 2025-02-28 2024-10-31 0000819673 2025-02-27 false ~ http://www.MFS.com/20241031/role/RRSchedule4 ~ ~ http://www.MFS.com/20241031/role/RRSchedule5 ~ ~ http://www.MFS.com/20241031/role/RRSchedule6 ~ ~ http://www.MFS.com/20241031/role/RRSchedule7 ~ ~ http://www.MFS.com/20241031/role/RRBarChart8 ~ ~ http://www.MFS.com/20241031/role/RRSchedule9 ~ ~ http://www.MFS.com/20241031/role/RRSchedule13 ~ ~ http://www.MFS.com/20241031/role/RRSchedule14 ~ ~ http://www.MFS.com/20241031/role/RRSchedule15 ~ ~ http://www.MFS.com/20241031/role/RRSchedule16 ~ ~ http://www.MFS.com/20241031/role/RRBarChart17 ~ ~ http://www.MFS.com/20241031/role/RRSchedule18 ~ -0.0201 0.0508 0.3138 -0.0494 0.3535 0.2023 0.1836 -0.193 0.206 0.1068 -0.0207 0.0784 0.0568 -0.0239 0.1133 0.0945 -0.003 -0.1357 0.0744 0.0264 This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase. February 28, 2026 February 28, 2026 February 28, 2026 February 28, 2026 February 28, 2026 February 28, 2026 February 28, 2026 February 28, 2026 February 28, 2026 This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase. February 28, 2026 February 28, 2026 February 28, 2026 February 28, 2026 February 28, 2026 ~ http://www.MFS.com/20241031/role/RRSchedule10 ~ ~ http://www.MFS.com/20241031/role/RRSchedule19 ~ 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 February 28, 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 1.22% of the class' average daily net assets annually for each of Class A and Class R3 shares, 1.97% of the class' average daily net assets annually for each of Class B, Class C, and Class R1 shares, 0.97% of the class' average daily net assets annually for each of Class I and Class R4 shares, 1.47% of the class' average daily net assets annually for Class R2 shares, and 0.90% 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 February 28, 2026. 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 reduce its management fee to 0.40% of the fund's average daily net assets annually up to $2.5 billion. This written agreement will remain in effect until modified by the fund's Board of Trustees, but such agreement will continue until at least February 28, 2026. 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 February 28, 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 0.73% of the class' average daily net assets annually for Class A shares, 1.48% of the class' average daily net assets annually for each of Class B and Class C shares, 0.48% of the class' average daily net assets annually for Class I shares, and 0.40% 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 February 28, 2026. Shares automatically convert to Class A shares approximately eight years after purchase; therefore, the expense examples reflect Class A share expenses after eight years.