An announcement that the government would intervene in the troubled lending giants Freddie Mac and Fannie Mae made long-term mortgage rates drop. The average rate on a 30-year, fixed-rate mortgage has fallen to 5.88 percent, down from 6.26 percent last week, according to Bankrate.

The average rate on a 15-year loan fell to 5.49 percent, down from 5.77 percent during the week prior. For the mortgage market, that represents a huge drop, virtually overnight.

Mortgage rates fell because the government stepped in to guarantee billions of dollars in outstanding mortgage-backed securities issued by Fannie and Freddie, making them instantly more desirable to investors.

As investors bid up the price of mortgage-backed securities, that sent interest rates tumbling, with the average 30-year fixed rate falling below 6 percent for the first time since January, when rates stayed down only briefly.

This time, lenders say, rates are likely to stay low for much longer — good for homeowners, prospective buyers and the troubled real estate industry.

But for buyers or homeowners who want to refinance, the lower rates are good news, and brokers are hoping for a wave of new business.

But other brokers note that, while the newly lowered rates could last for a few months, they won’t stay below 6 percent forever and could climb back up to about 6.5 percent over the next year.