But the news does help insulate Cohen, even if it doesn’t help Martoma very much. No one knows what Martoma told Cohen before Cohen made the decision to go flat, but SAC’s trading action is entirely consistent with a simple declaration that Martoma wasn’t comfortable being long any more. (The rest of SAC was already making a strong case against being long at this point.) If Cohen knew that an announcement was imminent, and that the one person who wanted to be long no longer wanted to be long, then it would have made sense for him to go flat ahead of the announcement, even if he had no inside information at all. And there’s no particular reason to believe that Martoma would have admitted to Cohen that he had illegal insider information.
As Sorkin and Lattman say, the statute of limitations on this trade is rapidly running out: if the SEC will have to either bring charges against Cohen soon, or not at all. And so long as Martoma is refusing to cooperate with the SEC, it increasingly seems as though the SEC’s best chance yet to nail Cohen is going to slip through its hands.