WaMu was sold by regulators in September
JP Morgan Chase is to cut about 9,200 jobs at the former Washington Mutual (WaMu), the largest US bank to fail.
Regulators were forced to take control and sell off the mortgage lender at the end of September.
The cuts amount to more than a fifth of the workforce at WaMu. About 4,000 posts will go by the end of January.
JP Morgan bought most of WaMu's assets from regulators for $1.9bn (£1.3bn) as the bank became one of the biggest victims of the ongoing credit crunch.
JP Morgan spokesman Christine Hovelas said the remaining 5,200 jobs would be eliminated by the end of 2009.
She added that JP Morgan had not made a decision on what to do with WaMu's headquarters building in Seattle.
WaMu was JPMorgan's second big fire-sale acquisition since the start of the credit crunch. It also bought Bear Stearns in March.
The WaMu deal turned JP Morgan into the second-biggest US bank, with 5,410 branches in 23 states, of which it plans to close no more than 10%.