Research by the UNC Tax Center shows just six publicly traded U.S. companies, including Amazon and Warren Buffett’s Berkshire Hathaway Inc., would have paid half the estimated $32 billion in revenue generated by a 15% corporate minimum tax signed into law last month. “Who actually pays a lot is just not very many firms at all,” said Jeff Hoopes, UNC Kenan-Flagler Business School professor and the center’s research director. “My guess is it will not be the same firms every single year.” The study, co-authored by Hoopes and Research Associate Christian Kindt, received coverage in the Wall Street Journal, Barron’s, Bloomberg, Yahoo! Finance and CNBC.