The ex-JPMorgan Chase trader nicknamed \"the London Whale\" for his huge derivatives losses has reached a deal to avoid US prosecution, a source familiar with the situation said Tuesday. Bruno Iksil, who along with others has been blamed for big bets that resulted in a $6.2 billion loss for the bank in 2012, reached the deal after agreeing to testify in the case. Criminal indictments against two other ex-JPMorgan traders could come later this week.