Average 30-year mortgage rate jumps to 4.46%

• Average rate is up from 4.29%25 last week
• Average 15-year mortgage rate rose to 3.47%25
• Five-year adjustable mortgage remained at 2.99%25

WASHINGTON (AP) — Average U.S. rates for fixed mortgages rose sharply this week, making home-buying slightly less affordable.

Mortgage buyer Freddie Mac said Thursday the average rate on the 30-year loan jumped to 4.46% from 4.29% last week. The average on the 15-year fixed loan increased to 3.47% from 3.30%.

Rates have risen a full percentage point since May after the Federal Reserve signaled it might slow its bond purchases by year's end. Rates peaked at 4.6% in August.

Mortgage rates have stabilized since September, when the Fed surprised markets by taking no action. And rates remain low by historic standards. The Fed meets later this month and could slow the bond purchases if the economy shows further improvement.

The bond purchases are designed to keep long-term rates low.

The increase in mortgage rates has contributed to a slowdown in home sales over the past two months. But the government reported Wednesday that purchases of new homes ramped up in October after three months of soft sales, evidence that the housing market is improving fitfully.

Sales of new homes increased 25.4% to a seasonally adjusted annual rate of 444,000 in October, the largest monthly percentage increase since May 1980.

And in another sign of potential economic strength, the Commerce Department said Thursday the economy grew at a 3.6% annual rate from July through September, the fastest since early 2012. But nearly half the growth came from a buildup in business stockpiles, a trend that could reverse in the current quarter and hold back growth.

To calculate average mortgage rates, Freddie Mac surveys lenders across the country on Monday through 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 fell to 0.5 point from 0.7 point. The fee for a 15-year loan dropped to 0.4 point from 0.7 point.

The average rate on a one-year adjustable-rate mortgage ticked down to 2.59% from 2.60% last week. The fee was unchanged at 0.4 point.

The average rate on a five-year adjustable mortgage jumped to 2.99% from 2.94% last week. The fee declined to 0.4 point from 0.5 point.