EVP and COO, Walmart U.S., Walmart, 51
McKenna is playing a crucial role as Walmart amps up its battle against Amazon. As COO of the $308 billion U.S. business, she’s preparing for an e-commerce world by fast-tracking the rollout of an online grocery pickup program to almost 1,100 locations by the end of January. In test mode: a high-tech vending machine for online orders and a program that has store employees delivering some digital purchases. In August the U.S. business had its 11th quarter in a row of a rise in customer store visits.