NEW YORK (AP) — A former hedge fund portfolio manager was arrested Tuesday on charges that he helped deliver what a prosecutor said "what might be the most lucrative inside tip of all time," enabling investment advisers and their hedge funds to make more than $276 million in illegal profits.

Mathew Martoma was charged in U.S. District Court in Manhattan with using confidential information about an Alzheimer's disease drug trial to help his firm avoid losses and instead reap a hefty profit in a scheme that stretched from 2006 through July 2008 while he worked for CR Intrinsic Investors LLC of Stamford, Conn. He's charged with conspiracy to commit securities fraud and two counts of securities fraud.

"The charges unsealed today describe cheating coming and going — specifically, insider trading first on the long side, and then on the short side, on a scale that has no historical precedent," U.S. Attorney Preet Bharara said in a statement.