Bloomberg reported that after saving JPMorgan from the ravages of the London Whale, Andrew Feldstein, who leads BlueMountain Capital Management, is offering to help other banks unwind their bad derivatives bets.

Bloomberg said that Feldstein is best known for his June coup, when he bet against the London Whale – JPMorgan Chase trader Bruno Iksil – who was long and wrong on $100 billion in credit derivatives. Bloomberg notes, according to people familiar with the matter, that the play reaped $300 million for BlueMountain. Feldstein did more than make money, Bloomberg says, he also helped CEO Jamie Dimon unwind JPMorgan’s trades, earning points with America’s most powerful banker.

To read the Bloomberg story, click here.