You’ve read all of your free items this month. To register, get added benefits and unlimited access to articles, Become a Member. Already a Member? Sign in. Advertising Age Article Abstract Omnicom-Publicis Bust-Up Shows Limits of Holding Co. Model Linking Two Behemoths Failed, and Targets That Move the Needle Are Scarce By Matt Quinn and Alexandra Bruell, Published on May 11, 2014 1 Want more Access, Content & Connections? Upgrade to Membership. We are glad you are enjoying Advertising Age. To get uninterrupted access and additional benefits, become a member today. Become a Member Already a member? Log in.