Strategy. MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests at least 80% of the funds net assets in U.S. Government securities. MFS may also invest the fund's assets in other debt instruments. 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 generally invests substantially all of the funds 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, … Show more… MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests at least 80% of the funds net assets in U.S. Government securities. MFS may also invest the fund's assets in other debt instruments. 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 generally invests substantially all of the funds 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 funds assets in foreign securities. MFS may invest a significant percentage of the funds assets in a single issuer or a small number of issuers. MFS may engage in active and frequent trading in pursuing the funds 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 bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual instruments and their issuers. Quantitative screening tools that systematically evaluate instruments may also be considered. In structuring the fund, MFS also considers top-down factors. For purposes of the fund's 80% policy, net assets include the amount of any borrowings for investment purposes. Show less