US banking giant JPMorgan Chase on Thursday revealed that it would incur losses that could run into the billions as a result of bad bets on derivatives.
In a unscheduled conference call, chief executive Jamie Dimon reported the trades cost the company around $2 billion in recent weeks, half of which was clawed back.
It "could cost us as much as one billion dollars," Dimon said, admitting that how markets react in the coming days and weeks could put the final price tag much higher.
"It could get worse."
The losses were linked to JPMorgan's Chief Investment Office, which hedged the firm's assets and liabilities against synthetic credit derivatives.
"These were egregious mistakes," Dimon said. "They were self-inflicted and this is not how we want to run a business."
JPMorgan shares fell 5.5 percent in after-hours trade.
The losses are a humiliation for Dimon -- one of Wall Street's best known titans -- and for the bank, coming hot on the heels of the 2008 financial crisis.
Then, the collapse of the market in mortgage derivatives punched a giant hole in banks' balance sheets and plunged the world's largest economy into the worst recession in a generation, costing millions of jobs.
As recently as last month, JPMorgan executives told investors they were "very comfortable" with positions held by the bank, raising questions about how much was known by senior management and when.
The revelations are also likely to fuel debate about President Barack Obama's sweeping reforms of Wall Street.
Under rules still being finalized, banks would see limits on how much they can trade for their own benefit using deposits, the so-called Volcker rule.
Wall Street has fiercely opposed curbs on this sometimes lucrative trade.