The fund generally will invest at least 80% of its assets in the component securities of the underlying index and may invest up to 20% of its assets in certain futures, options and swap contracts, cash and cash equivalents, including shares of money market funds advised by BFA or its affiliates, as well as in securities not included in the underlying index, but which BFA believes will help the fund track the underlying index. The index is based on a traditional market capitalization-weighted parent index, the MSCI USA Index (the parent index).