John Wren, chief executive officer of Omnicom Group Inc., gestures during a news conference at the Publicis headquarters in Paris, France, on Sunday, July 28, 2013. Publicis Groupe SA and Omnicom Group Inc. agreed to merge in an all-stock transaction to create the world's largest advertising company with $23 billion in revenue, toppling market leader WPP Plc. Photographer: Balint Porneczi/Bloomberg via Getty Images