Buffett (pictured) bought 40.1m shares in the firm, the world’s largest publicly traded oil company, according to a regulatory filing for Q2, representing 0.9% of the group’s shares. 

Exxon shares rose 84 cents or 0.9% to $94.06 in after hours trading following the disclosure by America’s second-richest person to the US Securities and Exchange Commission (SEC).

Buffett last owned Exxon Mobil in late 2011 and the stock has lagged the market in the past three years.

Buffett reduced exposure to another oil company, ConocoPhilips, by 44% in September.

In its latest filing, Berkshire Hathaway reported it holds $104.9bn in equities and owns more than 80 businesses.