A federal grand jury in New York returned an indictment Friday against a former SAC Capital portfolio manager previously charged in what prosecutors have called the "most lucrative" insider trading scheme ever.

Mathew Martoma, 38, of Boca Raton, Florida, was indicted on three counts of conspiracy to commit securities fraud and securities fraud related to trades made in Elan Corp Plc and Wyeth based on tips prosecutors say he received from a doctor.

The trades allegedly helped Steven A. Cohen's SAC Capital hedge fund avoid losses and reap profits totaling $276 million in the summer of 2008. The indictment followed an earlier criminal complaint federal prosecutors filed Nov. 20.