Rates on 30-year mortgages, which had been falling for five weeks, jumped sharply this week, reflecting the turbulence in global credit markets.

Freddie Mac reported Thursday that its nationwide survey found that the average for 30-year, fixed-rate mortgages rose to 6.09 percent this week, up from 5.78 percent last week. Last week's rate had been the lowest level for 30-year rates since February.