The investment seeks to track the investment results of the Morningstar® U.S. Bond Market Yield-Optimized IndexSM. The fund generally will invest at least 90% of its assets in the component securities of the underlying index and may invest up to 10% of its assets in certain futures, options and swap contracts, cash and cash equivalents, including shares of BlackRock Cash Funds, as well as in securities not included in the underlying index, but which BFA believes will help the fund track the underlying index. The underlying index is a broadly diversified fixed-income index that seeks to deliver current income while maintaining long-term capital appreciation.