The number of mortgage applications filed last week fell to the lowest level since May 2002, more evidence of an end to the five-year boom in housing.

The Mortgage Bankers Association said yesterday its index of applications to buy a home or refinance an existing mortgage declined 1.5% to 545.9 last week, the fourth straight decrease, from 554.1 a week earlier.

The group’s measure of purchases dropped to the lowest level since February, even as borrowing costs fell, suggesting a weakening in the housing market that will help slow the economy.

“An air of caution has entered the housing industry,” said Chris Rupkey, senior financial economist at Bank of Tokyo-Mitsubishi Ltd. in New York. “You have to be pretty brave to buy at a time when many people feel there’s a bubble out there.”

The gauge of applications to purchase homes fell 3.4% to 418.3, the lowest since February 18, from 432.9 the week before. The group’s gauge of refinancing rose 8.3% to 1363.2 from 1259.1.

“I wouldn’t panic at this juncture,” a senior vice president at PNC Financial Services, Nick Buss, said in an interview from Pittsburgh. “Overall, it’s showing that we’re slowing at a fairly measured pace.”

The average rate on a 30-year fixed mortgage dropped to 6.15% last week from 6.21% a week earlier. The rate is up from 5.7% the same week a year ago.

At the current mortgage rate, the cost for every $100,000 of a loan would be $609.23 a month. When the rate, as measured by the Mortgage Bankers Association, was at a record low of 4.99% in June 2003, the cost was $536.21 a month.

The share of mortgage applications for refinancing increased to 42.7% from 40.2% the previous week.

The gain was partly due to borrowers shifting from adjustable-rate loans to fixed rates, according to mortgage lenders. The average one-year adjustable rate increased to 5.41% last week from 5.36%, the mortgage bankers group said.

Robert Moulton, founder and president of Americana Mortgage Group Incorporated in Manhasset, N.Y., said he expects mortgage volume to decline by a third this year from 2005.

“It’s a combination of less refinancing activity and homes being on the market a little longer,” Mr. Moulton said. “We’re gradually converting into a buyer’s market because there’s so much inventory.”

Bruce Karatz, chief executive officer of KB Home, said speculators began their exodus from the housing market six months ago. The Los Angeles-based company is the fifth-largest American homebuilder by stock market value.

The president of Sierra Pacific Mortgage Company, James Coffrini, said speculators accounted for 15% to 20% of all home purchases at the height of the housing boom. The Rancho Cordova, Calif.-based company lends about $6 billion a year.

“We can feel the slowdown in our volume,” Mr. Coffrini said. “If I was speculator, I’d certainly be out.”

The National Association of Realtors forecast last month home sales of 8.1 million this year, the second-most on record, after an estimated record 8.4 million in 2005. The group said it expects an average 30-year fixed rate of 6.5% this year, up from 5.8% in 2005.

Other economic reports also show evidence of waning home sales.