The largest agency merger in advertising history is no longer a plan. Omnicom completed its acquisition of Interpublic Group on November 26, 2025, in a deal valued at about $13.5 billion, creating a combined holding company with more than $25 billion in revenue — larger than WPP, its nearest rival, and large enough that the industry shorthand has shifted from a “big six” to three dominant networks: Omnicom, WPP and Publicis Groupe.
The integration since the close has been sweeping. In February 2026, Omnicom Public Relations Group consolidated its overlapping brands: Golin and Ketchum merged into a combined network, Porter Novelli was absorbed into FleishmanHillard, and R&CPMK was dissolved, leaving four cornerstone PR networks — Golin Ketchum, FleishmanHillard, Weber Shandwick and MMC. On the creative side, reporting on the new Omnicom structure shows three global networks — BBDO, McCann and TBWA — with storied names including DDB, FCB and MullenLowe retired as standalone brands, FCB folded into BBDO and DDB and MullenLowe rolled into TBWA. Media sits in a consolidated Omnicom Media Group spanning OMD, PHD, UM, Initiative, Mediahub, Hearts & Science and the data company Acxiom, which arrived with IPG.
The human cost is part of the story. Trade coverage citing the Financial Times reports more than 4,000 job cuts in the immediate post-merger integration, and IPG had already eliminated thousands of roles and vacated hundreds of thousands of square feet of office space during 2025 as it prepared for the close. The companies have targeted roughly $750 million in cost savings from combining the two groups.
For clients, the questions are practical. A merged Omnicom means account conflicts must be resolved inside a much larger roster, leadership and reporting lines are being redrawn region by region, and the combined group’s data and commerce assets — Acxiom’s identity data next to Omnicom’s Omni platform and Flywheel commerce network — are the strategic prize. Scale is the argument for the merger; whether scale produces better work is the argument clients will test through 2026 as integration teams compress more than a dozen legacy agencies into fewer, larger units, including a major reset of the Indian operation where the combined group becomes the market’s second-largest network.
Rivals are not standing still. WPP answered its slide to number two with its own consolidation around the Burson PR network and Ogilvy, plus portfolio simplification under new leadership. Publicis, which made no comparable mega-deal, competes on continuity. The independent sector, meanwhile, is pitching exactly what a merged giant cannot: senior attention, no conflicts and speed. The merger is done. The contest over whether bigger is better has about two years to run — and every client review in 2026 is a referendum on it.
