Activist investor Jana Partners discloses a 5.5% stake in Marathon Petroleum (MPC), according to...

|About: Marathon Petroleum Corp. (MPC)|By:, SA News Editor

Activist investor Jana Partners discloses a 5.5% stake in Marathon Petroleum (MPC), according to an SEC filing, apparently making Barry Rosenstein's hedge fund MPC's largest shareholder. Jana has built a track record of pressing companies - MHP, EP - to break up, but it's not yet clear what it wants this time. MPC +3.2% AH.