Buffett bought $10.7bn IBM stock since March

US billionaire Warren Buffett said on Monday he has bought $10.7 billion of IBM stock since March, the equivalent of a 5.5 percent share of the US information technology giant. Buffett, the 81-year-old tycoon who heads the Berkshire Hathaway financial holding company, told business channel CNBC that his investment amounts to some 64 million shares. Buffett, known as the "Sage of Omaha" for his investing skills, also said he increased his holdings in the leading US bank Wells Fargo, but did not give any figures. In late October IBM -- which celebrated its 100th anniversary in June -- named Virginia Rometty, 54, the current head of sales, marketing and strategy, to take over as chief executive on January 1, making her the first woman to lead the iconic US firm. Buffett's stock-picking prowess has made him the world's third-richest man, with a fortune of $50 billion, according to Forbes magazine's latest list of the world's billionaires.