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 Stat of the Day: How Big Is Big in the Ad Agency World? The Big Four Holding Cos. vs. the Rest By Matt Carmichael, Published on April 26, 2011 3 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. Register Now Already a member? Log in.