iShares S&P MidCap 400 Index Fund (the Fund) seeks investment results that correspond generally to the price and yield performance of the S&P MidCap 400 Index (the Index). The Index measures the performance of the mid-capitalization sector of the United States equity market, and consists of stocks that have a market capitalization between $1.5 billion and $5.5 billion (which may fluctuate depending on the overall level of the equity markets). The Fund invests in a representative sample of securities included in the Index that collectively has an investment profile similar to the Index. The Fund’s investment advisor is Barclays Global Fund Advisors.