 Berkshire Hathaway Inc has reduced its share count by 1.2 since April 23, a regulatory filing shows, suggesting that Chairman Warren Buffett might have become more aggressive in repurchasing its significantly underperforming stock. The reduction in the conglomerates outstanding shares was noted in a Wednesday filing concerning Buffetts 2.9 billion donation of Berkshire stock to five nonprofits, part of his pledge to give away nearly all his fortune. If Berkshire repurchased those shares, it might have conducted roughly 4.9 billion to 5.9 billion of buybacks, depending on the price, over 2-12 months, analysts said. 