MFS SERIES TRUST III
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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.
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Example
The annual fund operating expenses are based on estimated "Other Expenses" for the current fiscal year expressed as a percentage of the fund's estimated average net assets during the period.
The bar chart and performance table are not included because the fund has not had a full calendar year of operations.
Investment Objective
As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund.
Principal Risks
Shareholder Fees (fees paid directly from your investment):
Although your actual costs will likely be higher or lower, under these assumptions your costs would be:
Performance Information
<tt>MFS  (Massachusetts Financial Services Company, the fund's investment adviser)<br />normally invests at least 80% of the fund's net assets in high yielding debt<br />instruments.<br /> <br />MFS may invest the fund's assets in other types of debt instruments.<br /><br />Debt instruments include corporate bonds, foreign government securities,<br />asset-backed securities, and other obligations to repay money borrowed.<br /> <br />MFS may invest up to 100% of the fund's assets in less than investment grade<br />quality debt instruments (lower quality debt instruments).<br /><br />MFS may invest the fund's assets in foreign securities.<br /><br />While MFS may use derivatives for any investment purpose, to the extent MFS uses<br />derivatives, MFS expects to use derivatives primarily to increase or decrease<br />exposure to a particular market, segment of the market, or security, to increase<br />or decrease interest rate or currency exposure, or as alternatives to direct<br />investments. Derivatives include futures, forward contracts, options, structured<br />securities, inverse floating rate instruments, and swaps.<br /><br />MFS uses a bottom-up investment approach to buying and selling investments for<br />the fund. Investments are selected primarily based on fundamental analysis of<br />individual instruments and their issuers. Quantitative models that systematically <br />evaluate instruments may also be considered. In structuring the fund, MFS may <br />also consider top-down factors.</tt>
Summary of Key Information
Portfolio Turnover
<tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency.<br /><br />The principal risks of investing in the fund are:<br /><br />Interest Rate Risk:  The price of a debt instrument falls when interest rates<br />rise and rises when interest rates fall. Instruments with longer maturities, or<br />that do not pay current interest, are more sensitive to interest rate changes.<br /><br />Credit Risk:  The price of a debt instrument depends, in part, on the credit<br />quality of the issuer, borrower, counterparty, or underlying collateral or<br />assets and the terms of the instrument. The price of a debt instrument can<br />decline in response to changes in the financial condition of the issuer,<br />borrower, counterparty, or underlying collateral or assets, or changes in<br />specific or general market, economic, industry, political, regulatory,<br />geopolitical, or other conditions.<br /><br />Lower quality debt instruments (commonly referred to as "high yield securities"<br />or "junk bonds") can involve a substantially greater risk of default or can<br />already be in default, and their values can decline significantly. Lower quality<br />debt instruments are regarded as having predominantly speculative characteristics. <br />Lower quality debt instruments tend to be more sensitive to adverse news about <br />the issuer, or the market or economy in general, than higher quality debt <br />instruments.<br /><br />Foreign Risk:  Exposure to foreign markets through issuers or currencies can<br />involve additional risks relating to market, economic, political, regulatory,<br />geopolitical, or other conditions. These factors can make foreign investments,<br />especially those in emerging markets, more volatile and less liquid than U.S.<br />investments. In addition, foreign markets can react differently to these<br />conditions than the U.S. market.<br /><br />Derivatives Risk:  Derivatives can be highly volatile and involve risks in<br />addition to the risks of the underlying indicator(s) on which the derivative <br />is based. Gains or losses from derivatives can be substantially greater than <br />the derivatives' original cost.  Derivatives can involve leverage.<br /><br />Leveraging Risk:  Leverage involves investment exposure in an amount exceeding<br />the initial investment. Leverage can cause increased volatility by magnifying<br />gains or losses.<br /><br />Investment Selection Risk:  MFS' investment analysis and its selection of<br />investments may not produce the intended results and/or can lead to an<br />investment focus that results in the fund underperforming other funds with<br />similar investment strategies and/or underperforming the markets in which the<br />fund invests.<br /><br />Counterparty and Third Party Risk:  Transactions involving a counterparty or<br />third party other than the issuer of the instrument are subject to the credit<br />risk of the counterparty or third party, and to the counterparty's or third<br />party's ability to perform in accordance with the terms of the transaction.<br /><br />Liquidity Risk:  It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt>
Fees and Expenses
Principal Investment Strategies
<tt>The bar chart and performance table are not included because the fund has not<br />had a full calendar year of operations.</tt>
<tt>This table describes the fees and expenses that you may pay when you buy and<br />hold shares of the fund.<br /><br />The annual fund operating expenses are based on estimated "Other Expenses" for<br />the current fiscal year expressed as a percentage of the fund's estimated<br />average net assets during the period.</tt>
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Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):
<tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs and may result in higher taxes when <br />shares are held in a taxable account. These transaction costs, which are not <br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the <br />fund's performance.</tt>
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<tt>The fund's investment objective is to seek total return with an emphasis on high<br />current income, but also considering capital appreciation.</tt>
<tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds.<br /><br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt>
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