BOSTON ( TheStreet) -- Barry Rosenstein, founder of Jana Partners, is best known as an activist investor. The hedge fund manager made intriguing moves in the fourth quarter, buying more shares of Apple ( AAPL) and making an outsized bet on Marathon Petroleum ( MPC).In his role as an activist investor, Rosenstein has most recently targeted McGraw-Hill ( MHP), the owner of Standard & Poor's. Jana Partners previously initiated a stake in the company and hoped to break it up to unlock value. In September, McGraw-Hill announced that it would separate into two public companies, notching another victory for Rosenstein.
|Barry Rosenstein of Jana Partners hedge fund.|