Fixed mortgage were essentially unchanged this week, as the average rate on the 30-year fixed loan stayed below 5 percent.

Freddie Mac said Thursday the rate on the 30-year fixed mortgage rose to 4.87 percent from 4.86 percent the previous week. It hit a 40-year low of 4.17 percent in November.

The average rate on the 15-year fixed mortgage increased to 4.10 percent from 4.09 percent. It reached 3.57 percent in November, the lowest level on records dating back to 1991.

Mortgage rates tend to track the yield on the 10-year Treasury note.

Low rates have done little to boost home sales. KB Home was the latest homebuilder to report this week a sharp decline in home orders for the December-February quarter. The Los Angeles company said Tuesday that its new home orders dropped 32 percent from a year earlier, while the number of homes it delivered tumbled 28 percent.

Last week, Lennar Corp. posted similar results. Its new orders fell 12 percent in the same period and home deliveries slipped 3 percent.

Would-be buyers are reluctant to make purchases because of strict credit requirements, unemployment fears and expectations that home prices will fall further largely because of the record number of foreclosures still on the market.

To calculate average mortgage rates, Freddie Mac collects rates from lenders across the country on Monday through Wednesday of each week. Rates often fluctuate significantly, even within a single day.

The average rate on a five-year adjustable-rate mortgage rose to 3.72 percent from 3.70 percent. The five-year hit 3.25 percent last month, the lowest rate on records dating back to January 2005.

The average rate on a one-year adjustable-rate loan fell to 3.22 percent from 3.26 percent. Three weeks ago, the rate hit 3.17 percent, the lowest level on records dating back to 1984.

The rates do not include add-on fees, known as points. One point is equal to 1 percent of the total loan amount. The average fee for the 30-year fixed loan, 15-year fixed loan and the 1-year ARM in Freddie Mac's survey was 0.7 point. The average fee for the five-year ARM was 0.6 point.