MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests at least 80% of the fund’s net assets in debt instruments. Debt instruments include corporate debt instruments, U.S. Government securities, foreign government securities, securitized instruments (including mortgage-backed securities and other asset-backed securities), municipal instruments, and other obligations to repay money borrowed.

MFS generally focuses on investing the fund’s assets in investment grade quality debt instruments, but also typically invests a portion of the fund’s assets 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 may invest the fund’s assets in foreign securities, including emerging market securities. Emerging markets are countries determined to have emerging market economies based on factors that demonstrate the country's financial and capital markets are in the development phase.

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 may invest a significant percentage of the fund’s assets in a single issuer or a small number of issuers.

While MFS may use derivatives for any investment purpose, to the extent MFS uses derivatives, MFS expects to use derivatives primarily to increase or decrease exposure to a particular market, segment of the market, or security, to increase or decrease interest rate exposure, or as alternatives to direct investments. Derivatives include futures, forward contracts, options, and swaps.

MFS uses an active bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual instruments and their issuers. Quantitative screening tools that systematically evaluate instruments may also be considered. In structuring the fund, MFS also considers top-down factors.

The fund’s investment strategy is referred to as “Core Plus” because, in addition to investing in a core portfolio of investment grade quality debt instruments, MFS normally invests a portion of the fund’s assets in below investment grade quality debt instruments and/or emerging markets debt instruments.

For purposes of the fund's 80% policy, net assets include the amount of any borrowings for investment purposes.