Your parents might have told you that revenge solves nothing, but it's not clear that American banks have learned the same lesson. Bloomberg sources understand that the FBI is investigating whether or not US financial institutions hired hackers to conduct retaliatory hacks against Iran, crippling the servers that had been used to attack the companies starting in 2012. There isn't any hard evidence banks acted on their anger, although they at least came close. JPMorgan Chase acknowledged that one of its officials proposed an offshore strike that would have knocked the Iranian servers out of commission. The staffer didn't offer a full-fledged plan, however, and nothing appears to have come out of the idea.