One of the biggest successes in credit card history was cemented over a giant steak. It was early in COVID and American Express CEO Stephen Squeri—who had unexpectedly been named to the top job in 2016 (read the story of how, here)—was meeting with Delta CEO Ed Bastian in Atlanta to talk through the terms of their partnership. “I fed Steve a tomahawk at the Kevin Rathbun steak house,” Bastian recalls. The conversation topic? How to “stop fightin…