Omnicom is a marketing services holding company — and, following its late 2025 acquisition of IPG, the world's largest advertising holding company by revenue. Omnicom owns a portfolio of agencies that provide advertising, media buying, public relations, precision marketing, healthcare communications, and other marketing services to large global brands. The combined company employs approximately 120,000 people. Omnicom's top 100 clients generate roughly 54% of revenue, with no single client above 2.4% of revenue. Media & Advertising is the largest discipline, expected to represent roughly mid-50% of combined revenue, with key brands including OMD, PHD, BBDO, TBWA, and McCann. Other disciplines include Precision Marketing (CRM, data analytics, e-commerce), PR (FleishmanHillard, Ketchum, Weber Shandwick), Healthcare, and Experiential. Omnicom charges clients fees for services, with revenue driven by retainers, project work, and media buying — the latter increasingly through a principal model where Omnicom buys media inventory at scale and resells it at a markup. The largest cost is employee compensation. A key strategic asset is Omni, Omnicom's proprietary marketing intelligence platform, which integrates consumer identity data (via Acxiom), retail media and e-commerce optimization (via Flywheel), and AI-driven planning workflows across agency disciplines. Post-IPG, Omnicom is divesting roughly $3.2B in non-strategic revenue and targeting $1.5B in annual run-rate cost synergies, concentrating investment in Media, Precision Marketing, and Healthcare.