Omnicom-IPG Merger Faces Surprise FTC Challenge Over Data Dominance

The Federal Trade Commission on Tuesday filed a formal challenge to the proposed $30.2 billion merger between Omnicom Group and Interpublic Group, injecting sudden uncertainty into a deal that both companies had publicly described as all but complete. The complaint, filed in federal court in Washington, D.C., centers not on the traditional antitrust concern of market concentration in media buying, but on something regulators view as far more consequential: the combined entity's control of first-party consumer data.

The FTC's 47-page complaint alleges that a merged Omnicom-IPG would control consumer data assets touching approximately 320 million unique profiles in the United States alone, drawn from Omnicom's Omni platform and IPG's Acxiom division, which the company acquired for $2.3 billion in 2018. Regulators argue that this concentration would give the combined company "undue leverage" over both advertisers and publishers, effectively allowing it to set pricing terms for data-driven advertising across the open web.

"This is not a traditional media buying case," said FTC Chair Lina Khan in a statement accompanying the filing. "This is about whether a single corporate entity should control the data infrastructure that underpins the modern advertising economy. The answer, in our view, is no."

The challenge caught Wall Street off guard. Shares of Omnicom fell 11.4 percent in afternoon trading, while IPG dropped 8.7 percent. Analysts at Morgan Stanley downgraded both stocks to "equal weight" within hours of the filing, citing the likelihood of a protracted legal battle that could delay or scuttle the transaction entirely. The deal, first announced in December 2025, had been expected to close by mid-2026.

At the heart of the FTC's case is a relatively novel legal theory: that first-party data, assembled over years through loyalty programs, purchase histories, and device-level tracking, constitutes a form of market infrastructure rather than a conventional business asset. The complaint draws an analogy to railroad consolidation in the early twentieth century, arguing that Acxiom's data serves as a "common carrier" for thousands of advertisers and that concentrating it under Omnicom's roof would create an entity with both the incentive and the ability to discriminate against competitors.

Omnicom and IPG issued a joint statement calling the FTC's action "legally unfounded and economically misguided." The companies argued that the advertising data market is "intensely competitive," pointing to Google, Meta, Amazon, and The Trade Desk as entities with far larger data assets. "The combined Omnicom-IPG would control less than 15 percent of addressable advertising data in the U.S.," the statement read. "This challenge ignores the massive scale of the walled gardens and substitutes regulatory theory for market reality."

Legal experts are divided on the FTC's chances. Traditional antitrust analysis focuses on market share in defined product markets — typically media buying, creative services, or specific advertising verticals. By those measures, the combined Omnicom-IPG would hold roughly 25 percent of the U.S. agency market, a level that has historically passed regulatory review. But the FTC's data-centric theory asks the court to define an entirely new market — one for "advertising data infrastructure" — and courts have been slow to adopt novel market definitions in merger cases.

"The FTC is essentially asking the court to invent a new market and then block a merger based on dominance in that market," said Jonathan Baker, a former FTC Bureau of Economics director who now teaches at American University. "It's ambitious. It's not without precedent — the Microsoft case in the 1990s involved similar market-definition questions — but it's a heavy lift."

The timing also raises questions about broader regulatory strategy. The FTC has been increasingly aggressive under Khan's leadership, challenging deals in technology, healthcare, and now advertising. Some industry observers see the Omnicom-IPG case as a test balloon for a wider campaign against data consolidation across the digital economy. If the FTC prevails, the precedent could affect pending deals in ad tech, retail media, and health data.

For advertisers, the immediate impact is uncertainty. Several major brands that had begun planning for a combined Omnicom-IPG entity — including consolidated media buying and unified data platforms — are now pausing those preparations. "We were told this deal was a lock," said a chief marketing officer at a Fortune 100 consumer goods company who spoke on condition of anonymity. "Now we're back to scenario planning. That costs time and money."

Both companies have indicated they intend to contest the challenge in court. A preliminary hearing is expected in late May, with a full trial potentially stretching into early 2027. In the meantime, the deal remains in limbo — and the advertising industry is left to grapple with a question it has never seriously confronted: whether the data that powers modern marketing has become too important to be owned by any single entity.