Sir Martin Sorrell, the former chief executive of advertising giant WPP Plc, described himself as a “realist” regarding the challenges facing traditional media and advertising companies and emphasized the need for scale during an interview at an ad-industry event. On stage with LUMA Partners CEO Terence Kawaja at the company’s Digital Media Summit in New York on Tuesday, Mr. Sorrell continued to point to the growing advertising and programming strength of Amazon.com Inc. and its potential to challenge television companies as well as the advertising duopoly of Google and Facebook Inc.
