But if you took out a five-year ARM, which has a fixed rate for the first five years, in mid-2005, that risk would have paid off. Compared with a 30-year conventional loan at the prevailing rate of 5.64 percent, a loan of $417,000 would have saved you roughly $10,080 in mortgage payments by now, assuming a five-year ARM rate of 4.99 percent, said Michele Raab-Francis, chief executive of Safe Harbor Capital, a mortgage broker in Bellport, N.Y.

With mortgage rates and many financial indexes low, and the economy showing no signs of a quick recovery, current ARM borrowers face an interesting choice. If they keep their loans, they may well have lower payments in the next year than those who have fixed-rate loans.

After the initial period, most ARMs are adjusted annually, at rates typically tied to one of three indexes: the one-year Constant Maturity Treasury Index; the Cost of Funds Index, known as the Cofi; or the London Interbank Offer Rate, known as the Libor. Borrowers whose ARMs are linked to the Treasury Index, for instance, would face one year of payments at a roughly 3 percent interest rate, according to Keith Gumbinger, a vice president of HSH Associates, a financial industry publisher and consulting firm. The Treasury rate may remain low since it generally rises when the economy strengthens.

Another option is refinancing to a fixed-rate loan while rates are at historic lows. Ms. Francis says this is especially popular with borrowers who have ARMs adjusted according to other indexes or have terms that allow for sharper interest rate spikes. But the cost of refinancing may be steep, especially in New York, where borrowers must pay a mortgage recording tax.

Ms. Francis suggested one other choice: converting the terms of an ARM with a current lender.

That is more feasible for borrowers who took out loans from regional banks and depositories instead of larger lenders like Citibank. Depositories tend to keep the mortgages on their books instead of selling them to investors.

Ms. Francis says these institutions will sometimes convert an ARM into a fixed-rate loan for a flat fee amounting to much less than the closing costs of refinancing. “It’s definitely worth it to at least call your lender in that circumstance,” she said.

For borrowers who want a jumbo loan — $729,750 or more in the greater New York area — an ARM may make more sense than a fixed-rate loan, she said.

Borrowers with excellent credit who need a $2 million loan, for example, can qualify for a 3/3 ARM, in which the rate resets every third year, at roughly 3.125 percent. That saves the borrower around $100,377 over three years, and when the loan adjusts in the fourth year, the rate can increase to no more than 5.5 percent — the same as the prevailing fixed rate jumbo loan today.

Some ARM borrowers hoping to refinance to a fixed-rate loan may be rejected if their homes are found to have lost too much value. But Anthony Hsieh, chief executive of LoanDepot.com, an online lender, said they might qualify for new loans.

For instance, Fannie Mae and Freddie Mac administer the federal government’s Home Affordable Finance program, in which borrowers whose mortgages exceed their homes’ value by as much as 25 percent may still qualify for a new loan. To qualify, a borrower’s current loan must be owned by either Fannie Mae or Freddie Mac. (You can find out if that is the case at fanniemae.com/loanlookup, or freddiemac.com/mymortgage.)

Borrowers must also be current on their loan payments, and the new loan must be deemed to put the borrower in a more financially stable situation than the old mortgage. Partly for that reason, borrowers whose mortgages exceed the value of their homes by more than 5 percent cannot refinance to an ARM.