(Reuters) JPMorgan Chase & Co said its traders may have deliberately hidden losses that have since climbed to $5.8 billion for the year, in a development that may result in criminal charges against traders at the bank.

The losses came from bets on corporate debt now known as the “London Whale” trades made at JPMorgan’s Chief Investment Office. Chief Executive Jamie Dimon said that in the worst-case scenario the derivatives trades would lose another $1.7 billion, and that the bank has fixed the CIO problems.

Investors cheered the bank for capping losses and taking steps to ensure it avoids similar bad bets in the future. JPMorgan’s shares rose nearly 6 percent on Friday.

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