A customer uses a Washington Mutual ATM in Palo Alto, Calif., on Thursday. (Paul Sakuma/Associated Press)

As the debate over a $700-billion US bank bailout rages on in Washington, one of the nation's largest banks — Washington Mutual Inc. — has collapsed under the weight of its enormous bad bets on the mortgage market.

Seattle-based WaMu, which was founded in 1889, is the largest bank to fail by far in the country's history. Its $307 billion in assets eclipse the $40 billion of Continental Illinois National Bank, which failed in 1984, and the $32 billion of IndyMac, which the government seized in July.

The Federal Deposit Insurance Corp. seized WaMu on Thursday, and then sold the thrift's banking assets to JPMorgan Chase & Co. for $1.9 billion US.

One positive is that the sale of WaMu's assets prevents the thrift's collapse from depleting the FDIC's insurance fund. But that detail is likely to give only marginal solace to Americans facing tighter lending and watching their stock portfolios plunge in the wake of the nation's most momentous financial crisis since the Great Depression.

Because of WaMu's souring mortgages and other risky debt, JPMorgan plans to write down WaMu's loan portfolio by about $31 billion — a figure that could change if the government goes through with its bailout plan and JPMorgan decides to take advantage of it.

"We're in favour of what the government is doing, but we're not relying on what the government is doing. We would've done it anyway," JPMorgan's chief executive, Jamie Dimon, said in a conference call Thursday night, referring to the acquisition. Dimon said he does not know if JPMorgan will take advantage of the bailout.

WaMu is JPMorgan Chase's second acquisition this year of a major financial institution hobbled by losing bets on mortgages. In March, JPMorgan bought the investment bank Bear Stearns Cos. for about $1.4 billion, plus another $900 million in stock ahead of the deal to secure it.

JPMorgan Chase is now the second-largest bank in the United States after Bank of America Corp., which recently bought Merrill Lynch in a flurry of events that included Lehman Brothers Holdings Inc. going bankrupt and American International Group Inc., the world's largest insurer, getting taken over by the government.

JPMorgan also said Thursday it plans to sell $8 billion in common stock to raise capital.

Failure anticipated

The downfall of WaMu has been widely anticipated for some time because of the company's heavy mortgage-related losses. As investors grew nervous about the bank's health, its stock price plummeted 95 per cent from a 52-week high of $36.47 to its close of $1.69 Thursday. On Wednesday, it suffered a ratings downgrade by Standard & Poor's that put it in danger of collapse.

WaMu "was under severe liquidity pressure," FDIC chair Sheila Bair told reporters in a conference call.

"For all depositors and other customers of Washington Mutual Bank, this is simply a combination of two banks," Bair said in a statement. "For bank customers, it will be a seamless transition. There will be no interruption in services and bank customers should expect business as usual come Friday morning."

Besides JPMorgan Chase, Wells Fargo & Co., Citigroup Inc., HSBC, Spain's Banco Santander and Toronto-Dominion Bank were also reportedly possible suitors. WaMu was believed to be talking to private equity firms as well.

The seizure by the government means shareholders' equity in WaMu was wiped out. The deal leaves private equity investors including the firm TPG Capital, which gave WaMu a cash infusion totalling $7 billion this spring, on the sidelines empty-handed.

WaMu ran into trouble after it got caught up in the once-booming subprime mortgage business. Troubles then spread to other parts of WaMu's home loan portfolio, namely its "option" adjustable-rate mortgage loans. Option ARM loans offer very low introductory payments and let borrowers defer some interest payments until later years. The bank stopped originating those loans in June.