Mortgage rates edged slightly lower during the week ended March 12 according to results from the Primary Mortgage Market Survey released by Freddie Mac on Thursday.

The 30-year fixed-rate mortgage (FRM) averaged 5.03 percent for the week, down from the week before when it averaged 5.15 percent.  Fees and points were unchanged at 0.7 point. 

15-year FRMs dropped 9 basis points from the previous week to an average rate of 4.99 percent.  Fees and points were also down from 0.7 point to 0.6.

Five-year Treasury-indexed hybrid adjustable rate mortgages (ARMs) behaved much like the 15-year fixed, going from 5.08 percent to 4.99 percent.  Fees and points were unchanged at 0.6 point.

One-year Treasury-indexed ARMs averaged 4.80 percent this week with 0.5 point, down from last week when the rate averaged 4.86 percent with 0.5 point.

"Mortgage rates had room to ease this week following news of a weaker jobs market, which may slow consumer spending and keep inflation at bay," said Frank Nothaft, Freddie Mac vice president and chief economist.  "The 30-year fixed-rate mortgage rate remains very close to January's all time recorded low of 4.96 percent.  Indeed, mortgage rates have drifted up and down only by about one-quarter of a percent in the first months of this year.

"Given the recent historically low mortgage rates, homeowners have a strong incentive to try and refinance.  For instance, the Bureau of Economic Analysis reports that the effective mortgage rate for loans outstanding in the fourth quarter of 2008 was around 6.2 percent, or almost 1.2 percentage points above this week's average rate for 30-year fixed-rate mortgages."

On Tuesday Fannie Mae released data on the average yield of its mortgages for the week that ended March 9.  All figures are net and do not include servicing fees.

The yield on Fannie Mae 30-year FRMs averaged 4.55 percent compared to 4.76 a week earlier.  The 15-year FRM was also down slightly, from 4.29 percent to 4.14 percent.  Government guaranteed FHA and VA 30-year FRM yields dropped from 6.20 percent to 6.01 percent.

The one-year ARM lost 8 basis points to 4.02 percent.