An index used to adjust the interest rate of an adjustable mortgage loan. For example: the change in U.S. Treasury securities (T-Bills) with a 1 year maturity. The weekly average yield on said securities, adjusted to a constant maturity of one year, which is the result of weekly sales, may be obtained weekly from the Federal Reserve Statistical Release H.15 (519). This change in interest rates is the “index” for the change in the specific Adjustable Mortgage Loan.