Rates for 30-year fixed loans rose to 5.21% for the week ended today from 5.08%, mortgage finance company Freddie Mac said in a statement. That’s the highest rate since the week ended Aug. 13. The average 15-year rate was 4.52%, according to the McLean, Virginia-based company.

Loan rates are climbing from record lows last year as the economy shows signs of strengthening and after the Federal Reserve completed a program of buying about $1.25 trillion of securities backed by U.S. residential mortgages. Rising borrowing rates and the expiration of homebuyer tax credits this month may reduce demand for homes.

“Higher borrowing costs of course will weigh on affordability,” said Michelle Meyer, U.S. economist at Barclays Capital Inc. in New York. “It is still a low rate relative to the historical average.”

Mortgage rates for 30-year loans may rise to 6% -- a level not seen since November 2008 -- by the end of the year, George Mokrzan, senior economist at Huntington National Bank in Columbus, Ohio, said before the data were released. A stronger economy and increased job creation may offset the negative effect on housing demand as consumers become more confident about making large purchases, he said.

U.S. gross domestic product grew at a 5.6% annual rate in the fourth quarter, the best performance in six years.

Homes for Sale - The number of existing homes for sale jumped 9.5% in February, data from the National Association of Realtors show. Government tax credits for first-time home buyers and some current owners expire April 30.

The Fed’s program of buying mortgage-backed securities, which ended last week, helped reduce rates to a record low of 4.71% in December. The average 30-year rate over the past decade is 6.2%, with a high of 8.64% in May 2000, Freddie Mac data show.

The government bond purchases from Fannie Mae, Freddie Mac and Ginnie Mae, agencies that buy home loans from lenders and package them into securities, brought down yields and allowed lenders to reduce mortgage rates while still selling the bonds at a profit.

The Mortgage Bankers Association’s index of mortgage applications fell 11% in the week ended April 2. The portion of refinancings dropped 17%. Applications to purchase a home increased 0.2%.