The Fund invests at least 80% of its net assets in U.S. fixed income securities, and in derivatives and other instruments that have economic characteristics and provide investment exposure similar to U.S. fixed income securities. U.S. fixed income securities include debt securities issued or guaranteed by the U.S. government, its agencies or instrumentalities and political sub-divisions (including inflation index linked securities and municipal bonds); U.S. corporate debt securities, including debentures, bonds (including zero coupon bonds), bankers acceptances (issued by industrial, utility, finance, commercial banking or bank holding company organizations), convertible and non-convertible notes, commercial paper, certificates of deposits, and freely transferable promissory notes; mortgage-backed securities; and asset-backed securities. U.S. fixed income securities also include securities included in the Bloomberg U.S. Aggregate Index.