A US Senate panel has issued a scathing assessment of JP Morgan's $6.2 billion (£4bn) trading loss last year.
The panel found that bank bosses ignored growing risks and hid losses from investors and federal regulators.
Executives at JP Morgan understated trading losses to state officials by hundreds of millions of dollars and dismissed questions about trading risks, according to the Senate subcommittee on investigations.
The report suggests that key executives, including CEO Jamie Dimon, were aware of huge losses at the bank even while they were downplaying the risks publicly.
"While we have repeatedly acknowledged mistakes, our management acted in good faith and never had any intent to mislead," the firm said.
But subcommittee chairman Senator Carl Levin said the probe showed "many, many failures" at the bank.