| An index is an economic indicator that lenders use to set the interest rate for an ARM. Generally the interest rate that you pay is a combination of the index rate and a pre-specified margin (profit margin). Two commonly used indices are the One-Year Treasury Bill and the London InterBank Offering Rate (LIBOR).
The Cost of Funds of the 11th District Federal Home Loan Bank (COFI) use to be popular for adjustable loans but is not typically used for new origiantions at this time. Loans based on this index typically allowed for negative amortization and huge payment increases after the first couple of years and were a large part of the mortgage meltdown of recent years. |