There’s a reason Jamie Dimon is the nation’s most powerful banker: he’s ruthless. The chairman of JPMorgan Chase and his shareholders successfully killed an investors’ proposal to strip him of his title and split the job between two people, sources said Tuesday. While the final tally of the vote has yet to be released, several shareholders who have seen the total confirmed that Dimon did in fact defeat the campaign. It’s not the first time investor groups have tried to oust the silver-haired chief executive officer. A similar proposal was brought to the table in 2011, but failed to pass, garnering only 40 percent of the vote.