Why John Mack left Rosneft after only a year By: CNBC.com News May 29, 2014 at 15:11 PM EDT A year after joining the Russian government-owned petroleum company Rosneft as a director, former Morgan Stanley chief executive John Mack is stepping down from it. Read More >> Related Stocks: BP Plc ADR Exxon Mobil Glencore Plc Morgan Stanley