Under normal market conditions, the fund invests at least 80% of its net assets in bonds of U.S. issuers, including government, corporate debt, mortgage-backed and asset-backed securities. It invests predominantly in investment grade debt securities and, under normal market conditions, is generally expected to have sector, credit and duration exposures comparable to the Bloomberg U.S. Aggregate Bond Index, the fund's benchmark index. The fund may enter into various interest rate and credit-related derivatives, principally U.S. Treasury futures, interest rate swaps and credit default swaps.