Mortgage rates headed down again, after lingering at a record low for two weeks.

The benchmark 30-year fixed-rate mortgage fell 5 basis points this week, to 4.45%, according to the Bankrate.com national survey of large lenders. A basis point is one-hundredth of 1 percentage point. In the 25-year history of Bankrate's weekly survey, the 30-year fixed has never been lower. The previous record, 4.5%, had been set in the previous two weeks. According to statistics compiled by the National Bureau of Economic Research, the last time mortgage rates were below 4.5% was in April 1953.

The mortgages in this week's survey had an average total of 0.32 discount and origination points. One year ago, the mortgage index was 5.22%; four weeks ago, it was 4.58%.

The benchmark 15-year fixed-rate mortgage fell 7 basis points, to 3.87%. The benchmark 5/1 adjustable-rate mortgage fell 4 basis points, to 3.64%, and the benchmark 30-year fixed jumbo fell 2 basis points, to 5.14%. All of those are record lows in Bankrate's survey; Bankrate has tracked the 5/1 ARM and 30-year jumbo since 2005.

Weekly national mortgage survey
Results of Bankrate.com's Oct. 6, 2010, weekly national survey of large lenders and the effect
on monthly payments for a $165,000 loan:

                                        30-year fixed   15-year fixed       5-year ARM
This week's rate:                4.45%             3.87%                3.64%
Change from last week:      -0.05               -0.07                 -0.04
Monthly payment:               $831.14          $1,209.76          $753.88
Change from last week:      -$4.89             -$5.77               -$3.72

It is possible Bankrate's survey caught rates in mid-plunge. While the survey was being conducted, payroll processor ADP reported that private-sector employers eliminated 39,000 jobs in September. Soon after this grim employment news, bond yields plummeted -- and mortgage rates followed.

"It's sure to help the affordability situation in housing," says Richard DeKaser, an economist and president of Woodley Park Research, a consulting firm based in Washington, D.C. He adds a caveat: Lending standards "remain extremely stringent and are available for only the most creditworthy borrowers."

Phenomenal rates

Jeff Lazerson, president of Mortgage Grader, a brokerage based in Laguna Niguel, Calif., says: "Business is just cranking. Rates are phenomenal -- I mean, just phenomenal." Then, he had to get off the phone -- too busy to talk.

The mortgage and real estate businesses probably got a boost toward the end of September because of changes made by the Federal Housing Administration.

Starting Oct. 4, the FHA began charging a smaller upfront insurance premium and a larger monthly premium. For the first time, the agency established a minimum credit score necessary to get an FHA-insured mortgage. It cut the amount of money sellers could contribute to closing costs, and it raised the minimum down payment required for people with low credit scores.

The chief economist for the Mortgage Bankers Association says the FHA changes probably drove last week's 9% increase in purchase applications.