The investment seeks to track the investment results of the Barclays U.S. Universal Index. The index measures the performance of U.S. dollar-denominated taxable bonds that are rated either investment-grade or high yield. The fund generally invests at least 80% of its assets in the securities of the underlying index. The fund may at times invest up to 20% of its assets in certain futures, options and swap contracts, cash and cash equivalents, including money market funds advised by BFA or its affiliates, as well as in securities not included in the index, but which BFA believes will help the fund track the index.