NEW YORK (Reuters) - The coronavirus pandemic may have erased around $64 billion of value from Warren Buffett's equity portfolio at Berkshire Hathaway Inc , setting up the conglomerate for one of the largest quarterly losses ever by an American company."The headline number will be ugly," said James Shanahan, an Edward Jones & Co analyst with a "buy" rating on Berkshire, referring to net results. Berkshire's portfolio of U.S.-listed stocks, including Kraft Heinz Co , may have shrunk by 26% in the..