Ad industry insiders say the Omnicom takeover of Interpublic Group could kick off more M&A. The US ad industry has barely grown over the past few years. AdvertisementSome industry insiders think the Omnicom-IPG tie-up is just the start of a massive reordering of the $70 billion ad agency industry and that it's only a matter of time before other holding companies are forced to acquire or be acquired as they look to bulk up. Private equity has been circlingThe big holding companies could also be a target for private-equity giants. Industry insiders have speculated for months that WPP, which once ranked as No.

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Persons: William Ritchie, Ritchie, Andreas Roell, Mark Read, Arthur, Sadoun, Tom Triscari, WPP's, Publicis, Omnicom, Havas, Mark Penn's Stagwell, Bill Koenigsberg, Martin Sorrell, David Morgan, Kepler, Blackstone, who's, Tata, Jay Friedman, They're Organizations: Interpublic, Insiders, WPP, Private, Accenture, Google, WY Partners, FGS, Evros, Publicis Groupe, Lemonade Projects, Vivendi, Horizon Media, Capital, Horizon, Temasek, Apollo, KKR, Industry, IBM, Tata Consultancy Services, Droga5, Goodway Locations: US, London