NEW YORK, N.Y. – A former SAC Capital Advisors portfolio manager has been convicted of helping his firm earn more than a quarter billion dollars illegally through insider trading.

The verdict for Mathew Martoma, of Boca Raton, Fla., was delivered Thursday in New York. Prosecutors say Martoma and his firm dumped millions of shares of two pharmaceutical companies after he learned in July 2008 about the secret results of an Alzheimer’s drug trial.

The government says Martoma corrupted a University of Michigan professor who was in charge of the safety committee for what was hoped to be a breakthrough drug to control the incurable memory-destroying disease.

Martoma’s attorney insisted his client made a sensible decision to sell the bloated stocks of the pharmaceutical companies that sponsored the drug trial.