Thursday, August 11th, 2011, 10:09 am

Mortgage interest rates plummeted to new lows this week as the economy felt the stings of European debt concerns and investors rushed to U.S. Treasurys, a scenario that pushed long-term yields lower.

The 30-year, fixed-rate mortgage fell to 4.32%, its lowest point this year. That's down from 4.39% last week and 4.44% a year earlier, Freddie Mac said in its primary mortgage market survey.

The 15-year, FRM decreased to 3.5% from 3.54% a week earlier and 3.92% last year. In addition, the five-year, Treasury-indexed hybrid, adjustable-rate mortgage hit 3.13%, down from 3.18% last week and 3.56% a year ago.

The one-year, Treasury-indexed ARM averaged 2.89%, down from 3.02% last week and 3.53% a year ago.

Frank Nothaft, vice president and chief economist for Freddie Mac, said mortgage rates eased even further when the Federal Reserve Open Market Committee ensured it would keep the federal funds rate low through at least mid-2013 to nurture anemic economic growth.

Bankrate.com also noted record lows for interest rates, saying credit rating downgrades to the country, Fannie Mae and Freddie Mac were good for mortgages and opened "the door to refinancing for homeowners that missed the chance last year."

The 30-year, FRM hit 4.46% in Bankrate's survey, down from 4.54% last week. Meanwhile the 15-year, FRM hit 3.61%, down from 3.68%.

The 5/1 ARM inched up from 3.23% to 3.24% based on Bankrate's analysis.

Write to: Kerri Panchuk.