Bloomberg Opinion columnist Barry Ritholtz speaks with Brad Stone, author of the just-published “Amazon Unbound: Jeff Bezos and the Invention of a Global Empire” and senior executive editor for technology at Bloomberg News. Stone is also the author of the New York Times bestseller “The Everything Store: Jeff Bezos and the Age of Amazon,” and “The Upstarts: Uber, Airbnb, and the Battle for the New Silicon Valley.”