Buffett sold 84% of his stake in Goldman Sachs, a longtime holding. : If this is your first time registering, please check your inbox for more information about the benefits of your Forbes account and what you can do next! Billionaire investor Warren Buffett, who told investors earlier this month that he had made a “mistake” betting on airlines, is continuing to sell stocks amid the coronavirus pandemic, the latest regulatory filing from Berkshire Hathaway shows.