Sen. Elizabeth Warren reignited her feud with Securities and Exchange Commission Chair Mary Jo White — and this time she’s dragging billionaire hedgie Steven Cohen into the middle of it. Warren on Thursday ripped into the SEC for allowing the former SAC Capital chieftain to start a new hedge fund firm just two months after he was barred from managing outside money until 2018. Cohen’s move has made a “mockery of the SEC’s core mission to protect investors,” Warren wrote in an open letter to White. In January, Cohen agreed to a two-year ban on managing outside money to resolve allegations of insider trading at his former firm. He didn’t admit to any wrongdoing as part of his agreement with the SEC.