FT Buffett now owns 1% of ExxonMobil Warren Buffett's Berkshire Hathaway disclosed it has purchased 40.1m shares of US oil and gas giant Exxonmobil, a stake now worth about $3.7bn. Exxon shares rose 0.68 per cent in after hours trading. The 13F filing to the SEC gives information current as of Sept 30. As the FT's Stephen Foley and Ed Crooks pointed out, the stakebuilding represents a bold move in a sector that has burned Mr Buffett in the past.