TRSY is passively managed to provide vanilla exposure to the ultra-short-term US Treasury bond segment. The fund holds a portfolio of US Treasurys with at least $300 million par amount outstanding and less than one year to maturity. Inflation-linked bonds, original-issue zero-coupon securities, floating rate notes, and STRIPS are excluded. The index is market-value-weighted based on amounts outstanding reduced by amounts held by the Federal Reserve's SOMA account. Accrued interest is calculated assuming next-day settlement. Cash flows from bond payments and redemptions are retained in the index until the end of the month and then removed as part of its monthly rebalancing. Note that cash does not earn any reinvestment income while held in the portfolio, thus causing a slight drag in the index performance. TRSY is not a money market fund and does not attempt to maintain a stable NAV.