The 15-year FRM this week averaged 4.33 percent with an average 0.7 point, down from last week when it averaged 4.40 percent. A year ago at this time, the 15-year FRM averaged 4.72 percent.

The 5-year Treasury-indexed hybrid adjustable-rate mortgage (ARM) averaged 4.11 percent this week, with an average 0.6 point, down from last week when it averaged 4.16 percent. A year ago, the 5-year ARM averaged 5.08 percent.

The 1-year Treasury-indexed ARM averaged 4.27 percent this week with an average 0.6 point, up from last week when it averaged 4.15 percent. At this time last year, the 1-year ARM averaged 4.86 percent.

"30-year fixed mortgages fell below 5 percent to match levels seen two weeks ago and are helping to maintain affordable home-purchase conditions," said Frank Nothaft, Freddie Mac vice president and chief economist. "In fact, monthly principal and interest mortgage payments for a typical family buying a median-priced home of $163,800 were just $709 in January, the lowest amount since February 1998, according to the National Association of Realtors® . For first-time homebuyers, the fourth quarter of 2009 was the third most affordable quarter since 1981 behind the first and second quarter of 2009."

"The federal tax credit for homebuyers, which expires on April 30th, may make housing even more affordable for some families already in the middle of the home buying process. In fact, the Federal Reserve's March 3rd regional economic review noted that several districts attributed stronger home sales to the homebuyer tax credit."