Rates for 30-year loans rose for the first time in 12 weeks as borrowers sought refinancings amid record-low borrowing costs.

The rate for a 30-year fixed loan climbed to 4.35% in the week that ended Thursday, from 4.32%, Freddie Mac said. The average 15-year rate was unchanged at a record low 3.83%, the company said.

A five-month slide in interest rates has spurred homeowners to seek lower monthly payments. The Mortgage Bankers Association's index of refinancings has more than doubled since the end of April.

That means banks can afford to let rates rise slightly, said Keith Gumbinger, vice president of HSH Associates, a Pompton Plains, N.J., publisher of consumer loan data.

Increased prepayments may also be pushing down mortgage bonds relative to Treasuries, he said.

"Refinance activity is pretty good right now, and lenders are reasonably busy," Gumbinger said. "So there's less of a need to slash interest rates to the bone to attract borrowers."

Investors may also have sold bonds to buy stocks, Gumbinger said. The Standard & Poor's 500 index gained 3.8% last week as better-than-estimated growth in private employment and manufacturing raised optimism the economy will avoid another recession.

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