Amazon appears poised to take the top spot on the Fortune 500, edging out Walmart for the first time in more than a decade. It’s a symbolic changing of the guard in corporate America, writes my colleague Phil Wahba in this must-read feature. For years, the rivalry between Amazon and Walmart looked like a fight over retail: e-commerce versus stores, software versus logistics, disruption versus incumbency. But Amazon’s rise to the top of the Fortune 500 points to a deeper leadership lesson, one that goes wel ...