JPMorgan Chase has suffered big, unexpected losses at a closely watched trading desk, providing fodder to supporters of a new financial regulation the bank's CEO has loudly opposed.

[Photo by: truthalliance.net]

The biggest U.S. bank by assets said on Thursday that it had lost $2 billion on bad bets on credit derivatives, made by a London trading desk, run by a man other traders have alternately dubbed "The London Whale" and "Voldemort." The office is intended to hedge the giant bank's credit risk, not increase it.

In a regulatory filing on Thursday, the bank said that, since the end of March, its chief investment office "has had significant mark-to-market losses in its synthetic credit portfolio, and this portfolio has proven to be riskier, more volatile and less effective as an economic hedge than the firm previously believed."

In a quickly scheduled conference call Thursday evening, CEO Jamie Dimon, who has been persistently critical of government efforts to regulate banks, said JPMorgan's trading losses were due to "egregious and self-inflicted mistakes," from trades that were "poorly executed and poorly monitored." Read more;