Interpublic Group

Formerly one of the four largest global advertising holding companies; now a wholly-owned subsidiary of Omnicom Group following the November 2025 merger close, forming the world's largest advertising group.

Omnicom Group's acquisition of Interpublic Group, announced December 2023, completed on November 26, 2025 after all regulatory approvals — making IPG a wholly-owned subsidiary of Omnicom. Interpublic Group (IPG) is a global advertising and marketing services holding company headquartered in New York City, housing some of the most recognized agency brands in the industry including McCann Worldgroup, FCB, MullenLowe, IPG Mediabrands, Weber Shandwick, and Acxiom. Founded in 1961 and built through decades of acquisitions and organic growth, IPG has served as a top-tier partner to multinational brands across virtually every industry vertical, offering integrated solutions spanning creative advertising, media planning and buying, data analytics, digital marketing, public relations, and experiential marketing. IPG's competitive differentiation has long rested on its open architecture model, which allows clients to assemble bespoke agency teams across IPG's portfolio rather than being locked into a single agency brand. Its acquisition of Acxiom's marketing services division in 2018 gave IPG a significant first-party data and identity resolution capability, positioning it ahead of many peers in the data-driven marketing era. IPG Mediabrands, housing agencies such as Initiative and UM, competes directly with the media investment arms of WPP, Publicis, and Omnicom for large-scale media mandates. In December 2023, Omnicom Group announced a definitive agreement to acquire Interpublic Group in an all-stock merger valued at approximately $13 billion. The deal received required regulatory approvals through 2024-2025 and closed on November 26, 2025, creating the world's largest advertising holding company. IPG's agency brands and capabilities — McCann Worldgroup, FCB, MullenLowe, IPG Mediabrands, Weber Shandwick, Acxiom — became part of the combined Omnicom-IPG entity, fundamentally reshaping the competitive landscape of the global advertising industry.