Hear from Walmart's CEO, StitchFix's founder, and more. : Good morning from Aspen! Fortune’s Brainstorm Tech conference kicks off today. You can watch the mainstage panels here starting at 2 p.m. Mountain Time (4 p.m. EST), and you’ll hear from: — Doug McMillon, CEO of Walmart: As the world’s largest retailer, what do you do to stay there? Online, digitally enabled brick and mortar stores, organic food, pick-up and delivery, massive advertising—how do you keep up? — Jamie Siminoff, founder of Ring: Ring went from Shark Tank rejection to Amazon acquisition.