Turbulent financial markets both here in the states and abroad served to push mortgage interest rates to new lows this week.

Despite the much-ballyhooed credit rating downgrade by Standard & Poor’s on debt issued by the United States, Fannie Mae, and Freddie Mac, investors made a run on what they still consider to be a safe place for their money, U.S. Treasury bonds, sending yields plummeting to near all-time lows. The trajectory of mortgage rates typically follows that of Treasury yields.

The Federal Reserve added to the forces driving rates lower with its pledge to keep a key interest rate near zero for at least the next two years. It’s the first time in two-and-a-half years the central bank has offered up guidance on a timeframe for any movement in the benchmark rate, foreshadowing extremely low interest rates for mortgage borrowers for some time to come.

Freddie Mac reported Thursday that the average 30-year fixed-rate mortgage dropped to 4.32 percent (0.7 point) for the week ending August 11, marking a new low for 2011. It dropped from 4.39 percent last week.

The 15-year fixed rate, 5-year adjustable-rate mortgage (ARM), and 1-year ARM all averaged new all-time record lows this week, according to the GSE.

The 15-year fixed rate came in at 3.50 percent (0.7 point) in Freddie’s survey. It was averaging 3.54 percent last week.

The 5-year ARM fell from 3.18 percent last week to 3.13 percent (0.5 point) this week. The 1-year ARM plunged from 3.02 percent to 2.89 percent (0.5 point).

Freddie Mac’s survey is based on data gathered from about 125 lenders across the country. A separate study by Bankrate, whose results are derived from data provided by the top 10 banks and thrifts in the top 10 U.S. markets, also showed new lows for 2011 across the board.

Bankrate pegged the average for the benchmark conforming 30-year fixed mortgage rate at 4.46 percent (0.36 point). That’s down from 4.54 percent last week.

The 15-year rate averaged 3.61 percent (0.35 point) in Bankrate’s survey this week, down from 3.68 percent last week.

Adjustable-rate mortgages also moved into record territory, with the average 7-year ARM dropping to 3.45 percent and the 10-year ARM falling to 3.93 percent, according to Bankrate, while the larger jumbo 30-year fixed rate set a new record low of 5.02 percent.

Complementing its rate report, Bankrate polls a panel of mortgage experts each week to gauge the direction of mortgage rates over the next seven days.

The panel is split this week, with 36 percent expecting mortgage rates to remain more or less unchanged over the next week, while an equal 36 percent forecast further declines. Just 28 percent predict any kind of rebound in the upcoming week.