BOSTON — Homeowners with mortgages of more than $1 million are defaulting at almost twice the U.S. rate and some are turning to so-called short sales to unload properties as stock-market losses and pay cuts squeeze wealthy borrowers.

"The rich aren't as rich as they used to be," said Alex Rodriguez, a Miami real estate agent with JM Group USA Inc., whose listings include a $2.9 million property marketed as a short sale because the price is less than the mortgage, leaving the bank with a loss. "People have reached the point where they can't afford the carrying expenses of a $2 million home."

Payments on about 12 percent of mortgages exceeding $1 million were 90 days or more overdue in September, compared with 6.3 percent on loans less than $250,000 and 7.4 percent on all U.S. mortgages, according to data from First American Core-Logic Inc., a Santa Ana, Calif.-based research firm. The rate for mortgages above $1 million was 4.7 percent a year earlier.

As defaults on the biggest mortgages rise, borrowers such as Steve Holzknecht are turning to short sales to exit loans that now are larger than the market value of the house. In such a transaction, the lender agrees to accept less than a 100 percent payoff on a mortgage to expedite the property's sale.

Holzknecht, 53, last month cut the asking price for his 7,280-square-foot home in Kirkland, Wash., by $550,000 to $1.25 million, lower than the balances of his two mortgages. Holzknecht, the former owner of Four Suns Inc., a Seattle luxury homebuilder that went out of business two months ago, constructed the Craftsman-style home in 2000. He declined to identify his lenders or the amount he owes.

"It's not uncommon to see this situation on the high end of the market — homes selling for less than it would cost to build them," said Holzknecht's agent, Joe Flick of Roanoke Group in Seattle. The property came on the market eight months ago priced at $1.85 million, he said.

Porter Michael Peterson, a 33-year-old linebacker for the National Football League's Atlanta Falcons, bought a mansion near Tampa, Fla., four months ago for $1.1 million — almost half the amount of the mortgage taken out by the sellers three years earlier, according to real estate records. Reggie Roberts, a spokesman for the Falcons, didn't return a call seeking comment.

Short sales almost tripled to 40,000 in the first six months of 2009 from the same period a year earlier, according to data from the Office of Thrift Supervision. The bank regulator doesn't break out short sales by size of mortgage.

"You are just starting to see the tip of the iceberg with luxury short sales," said Adrian Heyman, owner of Property Advisors, a real estate broker in Scottsdale, Ariz. "A lot of wealthy people are upside down in their mortgages and they just can't afford the second or third vacation home anymore."

There are 114,000 home loans of more than $1 million, according to First American. About a quarter of all mortgaged homes in the U.S. have loan balances bigger than their current value, known as being upside down or underwater, the data company said.

The Dow Jones Industrial Average lost more than half its value as it tumbled to a 12-year low in March. The number of U.S. households with a net worth of more than $1 million, not counting primary residences, fell to a five-year low of 6.7 million last year from a record 9.2 million in 2007, according to Spectrem Group, a Chicago-based consulting firm.

The financial-services industry was among the hardest hit by the recession. While Goldman Sachs Group Inc. set aside a record $16.7 billion in the first nine months of the year for employee bonuses, some Wall Street executives will see pay cuts, according to Johnson Associates Inc., a New York-based compensation-consulting firm.

Year-end bonuses for people at hedge funds, asset- management firms and insurance companies probably will drop an average 20 percent, the firm said.

"There's a lot of distress," said Tracy McLaughlin, co-owner of Morgan Lane Real Estate in Ross, Calif., north of San Francisco. "You have hedge-fund guys whose funds evaporated and a year-and-a-half later they're still not working."

The entry-level segment of the housing market was aided this year by an $8,000 first-time buyers tax credit that pushed resales to a 6.1 million annual pace in October, the highest since February 2007, the National Association of Realtors said in a Nov. 23 report.

President Obama signed a bill last month extending the program into next year. The new version keeps the first-time buyer benefit and makes a smaller credit available to some move-up buyers. It can't be used for homes priced above $800,000.