These mortgages offer low monthly payments, and are a good option for homebuyers who want the stability of an initial fixed rate combined with the increased buying power ARM loans offer. Adjustable rate mortgages (also called ARMs) have rates that are fixed for a specific period of time, after which the rate and your monthly payment are adjusted. They're different from fixed rate mortgages, whose interest rate and monthly payment do not change during the life of the loan.
With interest rates lower than most fixed rate mortgages, adjustable rate mortgages can be especially appealing to people looking to buy a home they plan on owning for just a few years. But adjustable rate mortgages are not for those leery of risk—there's always the chance that, after the initial fixed period, your rate and monthly payment could go up (or less likely, down) either slightly or drastically.
Adjustable rate mortgages are determined by two things: an economic index and a margin. Economic indices like LIBOR, COFI and Treasury securities are some of the most commonly used by lenders. Homebuyers taking advantage of ARMs should be aware of which index drives your loan, and should aim to find an index that has a history of stability