WASHINGTON (8/12/11)--Average rates on 30- and 15-year fixed rate mortgages fell to all-time lows this week, totaling 4.01% and 3.28%, respectively, Freddie Mac reported. Thirty-year mortgages averaged 4.09% last week and 4.32% this time last year. Fifteen-year mortgages averaged 3.29% last week and 3.75% this time last year. Freddie Mac Chief Economist Frank Nothaft said the record low fixed rates were partly due to the Federal Reserve’s recent decision to purchase billions in Treasury securities. However, Nothaft noted, interest rates for adjustable-rate mortgages (ARMs) “were nearly unchanged” due to this news, as short-term Treasury securities “serve as benchmarks for many ARMs.” Five-year Treasury indexed hybrid ARMs averaged 3.02%, equal to last week’s total. One-year Treasury-indexed ARMs averaged 2.83% this week, slightly up from the 2.82% total reported last week. These mortgages averaged 3.52% and 3.48%, respectively, this time last year. For the full release, use the resource link.