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Steven A. Cohen may not be a household name, but he's made a name for himself. In finance, fine art and sports, he's had an extraordinary run of success and has amassed assets worth more than $8 billion.

Lately, Cohen has been linked to what federal prosecutors in New York call history's most lucrative insider trading scheme, earning a quarter of a billion dollars. Cohen is not charged but authorities don't dispute characterizations of him as the "Hedge Fund Owner" repeatedly referenced in a criminal complaint against a former employee. The Securities and Exchange Commission has notified his firm, SAC Capital, that it is considering action.

Cohen reportedly assured investors his firm played by the rules. A spokesman says SAC and Cohen are cooperating and confident they acted appropriately.