This Web service Provides following monthly ,weekly and Historical Mortgage Indexes. There are many possible ARM indexes. Each one has distinct market characteristics and fluctuates differently. Constant Maturity Treasury (CMT) , Treasury Bill (T-Bill) , 12-Month Treasury Average (MTA) , Cost of Deposits Index (CODI) , 11th District Cost of Funds Index (COFI) , Cost of Savings Index (COSI) , London Inter Bank Offering Rates (LIBOR) , Certificates of Deposit (CD) Indexes , Prime Rate , Fannie Mae's Required Net Yield (RNY) .