Jan. 11 (Bloomberg) -- Brian Cohn, president of SAC Capital Advisors LLC, plans to leave the hedge-fund firm after working with founder Steven Cohen for 11 years.

Cohn, 40, will take time off and hasn't accepted another job. He joined Stamford, Connecticut-based SAC when it was about five years old and managed $300 million. The firm, once known for rapid stock trading, oversees $15 billion in equities, bonds, currencies and commodities, and takes longer term stakes in companies.

``We thank him for his many contributions to SAC's success and wish him all the best in his future endeavors,'' SAC spokesman Jonathan Gasthalter said today in an interview. Cohn declined to comment. His departure was reported earlier today by the Wall Street Journal.

Cohen, 51, generated returns averaging more than 40 percent a year through 2006. His SAC Capital International Fund gained 13 percent last year, trailing the firm's historical returns while beating the 10.4 percent average gain of managers, according to Chicago-based Hedge Fund Research Inc.

Cohn, who didn't make investments for SAC, previously spent about four years in New York and Ireland with International Fund Services, which provides operations and trading services for asset managers and is now a unit of Boston-based State Street Corp. He took time off earlier this year after his six-year-old son drowned in the family pool.

Separately, SAC's finance chief, James Rowen, will leave in about a month to become chief operating officer of Renaissance Technologies Corp., the East Setauket, New York-based hedge-fund firm run by James Simons. He's replacing Stephen Daffron, who went to Morgan Stanley.

Dan Berkowitz, who has overseen accounting and operations for SAC for almost eight years, will replace Rowen.

To contact the reporter on this story: Jenny Strasburg in New York at jstrasburg@bloomberg.net

Last Updated: January 11, 2008 18:27 EST