But other big investors have been buying the beleaguered rating agency, whose shares have fallen 19% this year. Berkshire, run by billionaire investor Warren Buffett, sold a million shares of the New York-based company in the first quarter ended March 31. Berkshire remains Moody's biggest single investor with a 31 million-share stake worth $663 million at quarter-end. Selling Moody's Berkshire also sold some shares of Kraft, the food company with which Buffett, right, had a clash over how the firm sought to pay for its acquisition of the Cadbury candy giant. Berkshire cut its Kraft stake by almost a quarter, to 106 million shares. With the latest round of sales, Berkshire has cut its Moody's holdings by a third since last summer. The move comes at a time when the rating agencies are under fire for their role in the housing bubble and facing regulatory curbs on what was their fastest-growing business.