The investment seeks to track the investment results of the Bloomberg Barclays U.S. Government/Credit Bond Index (the underlying index). The underlying index measures the performance of U.S. dollar-denominated U.S. Treasury bonds, government-related bonds and investment-grade U.S. corporate bonds that have a remaining maturity of greater than or equal to one year. The fund generally invests at least 90% of its assets in securities of the underlying index. It may invest the remainder of its assets in certain futures, options and swap contracts, cash and cash equivalents, as well as in securities not included in the underlying index.