Average U.S. rates on fixed mortgages rose this week in the wake of comments by Federal Reserve Chairman Janet Yellen suggesting that the Fed could start raising short-term interest rates by mid-2015.

Mortgage buyer Freddie Mac said Thursday the average rate for the 30-year loan increased to 4.40 percent from 4.32 percent last week. The average for the 15-year mortgage rose to 3.42 percent from 3.32 percent.

A key home-price index showed Tuesday a robust 13.2 percent increase in January compared with 12 months earlier. But the Standard & Poor’s/Case-Shiller 20-city index was down from a 13.4 percent increase in 2013 and was the second straight decline.

There have been signs recently that the home-sales market could pick up in the coming months.

Most economists expect sales to rebound as the weather improves and the spring buying season begins. Not only does warmer weather bring more traffic to open houses, but families are usually reluctant to move in the middle of the school year.

Mortgage rates have risen about a full percentage point since hitting record lows roughly a year ago.

The increase was driven by speculation that the Federal Reserve would reduce its $85 billion-a-month bond purchases, which have helped keep long-term interest rates low. Indeed, the Fed has announced three $10 billion declines in its monthly bond purchases since December. The latest plan is to cut its monthly long-term bond purchases to $55 billion because it thinks the economy is steadily healing.

The Fed also said after its two-day policy meeting last week that even after it raises short-term interest rates, the job market strengthens and inflation rises, the central bank expects its benchmark short-term rate to stay unusually low.

Yellen stressed that with the job market still weak, the Fed intends to keep short-term rates near zero for a “considerable” time and would raise them only gradually. Yellen also suggested that the Fed could start raising rates six months after it halts its monthly bond purchases, which most economists expect by year’s end. That means short-term rates could rise by mid-2015.

To calculate average mortgage rates, Freddie Mac surveys lenders across the country between Monday and Wednesday each week. The average doesn’t include extra fees, known as points, which most borrowers must pay to get the lowest rates. One point equals 1 percent of the loan amount.

The average fee for a 30-year mortgage was unchanged at 0.6 point. The fee for a 15-year loan also held steady at 0.6 point.

The average rate on a one-year adjustable-rate mortgage fell to 2.44 percent from 2.49 percent. The average fee remained at 0.4 point.

The average rate on a five-year adjustable mortgage increased to 3.10 percent from 3.02 percent. The fee rose to 0.5 point from 0.4 point.

(AP)