The fund's overall investment strategy is to match or incrementally exceed the performance of the U.S. investment-grade bond market. Under normal conditions, it will invest at least 80% of its net assets (including any borrowings for investment purposes) in bonds that are held in its benchmark index. The fund's holdings will normally include U.S. government and agency obligations, mortgage- and asset-backed securities, corporate bonds, and U.S. dollar-denominated securities of foreign issuers.