iShares S&P National AMT-Free Municipal Bond Fund (the Fund), formerly iShares S&P National Municipal Bond Fund, seeks results that correspond generally to the price and yield performance of the municipal bond sector of the United States as defined by the S&P National AMT-Free Municipal Bond Index (the Index). The Index measures the performance of the investment-grade segment of the United States municipal bond market. The Index includes municipal bonds from issuers that are primarily state or local governments or agencies (including the Commonwealth of Puerto Rico and the United States territories, such as the United States Virgin Islands and Guam) such that the interest on the bond is exempt from United States federal income taxes and the federal alternative minimum tax as determined by the index provider in accordance with its methodology. Its investment advisor is Barclays Global Fund Advisors.