Berkshire Hathaway released their most recent 13-F filing today. According to the filing Warren Buffett's company bought 40,089,371 shares of Exxon Mobil in the third quarter. Berkshire's stake accounts for about 1% of the oil giant. Share of Exxon Mobil are rising in after hours trading. Exxon shares closed at $93.22 today. Berkshire's stake in Exxon Mobil is worth $3.7 billion.