The Fund seeks to meet its investment objective generally by investing in individual securities which satisfy the criteria of the ICE 2031 Maturity US Treasury Index (the Underlying Index). The Fund will invest at least 80% of its assets in the component securities of the Underlying Index, and the Fund will invest at least 90% of its assets in U.S. Treasury securities that BFA believes will help the Fund track the Underlying Index, in each case except during the last months of the Fund's operations, as described below. The Fund will invest no more than 10% of its assets in futures, options and swaps contracts that BFA believes will help the Fund track the Underlying Index