WASHINGTON — Fixed mortgage rates have fallen to historic new lows for a fourth straight week and are likely to fall further.

Freddie Mac says the average on a 30-year fixed mortgage fell to 4.01 percent this week. That's the lowest rate since 1951.

The average on a 15-year fixed mortgage ticked down to 3.28 percent. Economists say that's the lowest rate ever for the loan.

Mortgage rates tend to track the yield on the 10-year Treasury note. Rates could fall further after the Federal Reserve announced last week that it would take further action to try to lower long-term rates.

But low rates have so far done little to boost home sales or refinancing. Many would-be buyers or homeowners don't have enough cash or home equity to get a new loan.

First Published September 29, 2011, 2:39 p.m.