US officials for the first time today implicated Steven Cohen, the founder of SAC Capital Advisors, in an alleged insider-trading scheme they said was the most lucrative ever to be charged.

In the criminal complaint unsealed today, federal prosecutors alleged Mathew Martoma, a portfolio manager at SAC Capital affiliate CR Intrinsic Investors, received confidential information over an 18 month period from a neurology professor about a trial for an Alzheimer's drug being jointly developed by Elan and Wyeth, which is now part of Pfizer. He allegedly purchased shares in the pharmaceutical companies and later sold their shares short when he learned negative news ahead of an announcement about the drug trial in 2008.