Warren Buffett, still greedy when others are fearful, brushes off coronavirus worries to widen Delta Air Lines stake The largest single investor in the Atlanta-based carrier, Buffett's Berkshire Hathaway now owns 71.9 million shares, or about 11.2 percent. Stock in Delta and its rivals has been hammered by worries that the coronavirus epidemic will curb travel. More on this For more news, please go to FoxBusiness.com and watch Fox Business Network.