Steven A. Cohen’s hedge fund, SAC Capital Advisors, has been doing really well. A little too well, if you ask the Securities and Exchange Commission (SEC). The regulator has accused many of SAC’s traders of insider trading over the years, but has never nailed the man himself, until now.

On Friday, the SEC charged Cohen, accusing him of ignoring “red flags” that indicated two of his traders were using illegal tips. The alleged insider trading occurred in 2008, by Matthew Martoma and Michael Steinberg, former SAC portfolio managers. Though both men face their own criminal and civil charges, they have both so far refused to settle or to throw Cohen under the bus.

While the SEC pursues its civil case against Cohen, the Department of Justice is coming at him from the other side with a criminal case. If the SEC prevails, Cohen could face a lifetime ban from trading and a hefty fine.

Cohen would be a big get for the agency; SAC is a big player on the markets, sometimes accounting for 3 percent of daily trading on the New York Stock Exchange.

“SAC is Steve Cohen,” former SEC Chairman Harvey Pitt told the Washington Post. “If he winds up being suspended or having his registration revoked, the game is over.”

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