Strategy. MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests directly and/or indirectly through investment in mutual funds advised by MFS at least 80% of the funds net assets in high income debt instruments. MFS may invest the funds assets in other types of debt instruments. Debt instruments include corporate bonds, foreign government securities, floating rate loans, and other obligations to repay money borrowed. MFS may invest up to 100% of the funds assets in below investment grade quality debt instruments. MFS may invest the funds 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 … Show more… MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests directly and/or indirectly through investment in mutual funds advised by MFS at least 80% of the funds net assets in high income debt instruments. MFS may invest the funds assets in other types of debt instruments. Debt instruments include corporate bonds, foreign government securities, floating rate loans, and other obligations to repay money borrowed. MFS may invest up to 100% of the funds assets in below investment grade quality debt instruments. MFS may invest the funds 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. 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. For purposes of the fund's 80% policy, net assets include the amount of any borrowings for investment purposes. Show less