IBM tumbles as Buffett discloses he is trimming stake

IBM shares tumbled Friday after billionaire investor Warren Buffett revealed he has sold about a third of his stake and "revalued" downward the computing giant. In early Wall Street trade, IBM shares were down 2.5 percent at $154.00. Buffett, one of IBM's biggest shareholders, told CNBC he had divested shares in the first and second quarter. "I don't value IBM the same way that I did six years ago when I started buying," he told the financial channel. "I've revalued it somewhat downward." Buffett added that "IBM is a big strong company, but they've got big strong competitors too." Buffett, who heads the Berkshire Hathaway holding company and is among the world's richest individuals, invested some $10.7 billion in IBM in 2011 for a stake of some 5.5 percent. His stake was worth an estimated $13.5 billion at the end of 2016. The move comes with Buffett set to release his closely followed annual shareholder letter, offering important clues for investors who follow his advice.