PIMCO 1-3 Year U.S. Treasury Index ETF, formerly PIMCO 1-3 Year U.S. Treasury Index Fund, is an exchange-traded fund. The Fund seeks to achieve its investment objective by investing under normal circumstances at least 80% of its total assets (exclusive of collateral held from securities lending) in the component securities (Component Securities) of The BofA Merrill Lynch 1-3 Year U.S. Treasury Index (the Index). The Index is an unmanaged index that tracks the performance of United States dollar denominated sovereign debt publicly issued by the United States Government having a maturity of at least one year and less than three years. The Fund may invest in derivative instruments, such as options, futures contracts or swap agreements. Pacific Investment Management Company LLC (PIMCO) serves as the investment manager for the Fund.