The investment seeks to track as closely as possible, before fees and expenses, the total return of the Barclays U.S. Aggregate Bond IndexSM. The fund invests at least 90% of its net assets in securities included in the index. The index is a broad based benchmark measuring the performance of the U.S. investment grade, taxable bond market, including U.S. Treasuries, government-related and corporate bonds, mortgage pass-through securities, commercial mortgage-backed securities, and asset-backed securities that are publicly available for sale in the United States.