Adtech platform PubMatic has filed an antitrust lawsuit against Google, alleging the company unlawfully maintained monopolies across key layers of the digital advertising stack. The complaint seeks billions in damages and argues that Google’s control over publisher ad serving and exchange auctions has throttled competition and innovation, according to reporting by Bloomberg.
The case lands on the heels of a landmark federal ruling that found Google illegally monopolized ad exchanges and ad servers, with a separate remedies proceeding expected to consider potential structural changes to Google’s ad business. PubMatic’s move signals that independent exchanges and sell-side platforms see a window to challenge longstanding market dynamics they say have tilted the field.
What PubMatic alleges
PubMatic contends Google leveraged its dominance in publisher ad serving via Google Ad Manager to advantage its own exchange, AdX, through preferential auction mechanics, discriminatory fees, and product designs that blunted rivals. The complaint is expected to spotlight practices previously scrutinized by regulators and courts, including “last look” advantages, dynamic allocation, and the steering of demand toward Google-run pipes.
The suit also challenges Google’s approach to header bidding versus its own server-side alternative, Open Bidding. PubMatic and other independents argue Google used control points to make independent header bidding slower or less effective, then positioned its integrated solution as the “safer” default. Similar claims have appeared in state-led and federal cases, as well as in publisher suits that alleged Google quietly operated programs—such as the so-called Project Bernanke—that shaped auction outcomes in its favor. Google has disputed those characterizations and said its optimizations benefited buyers and sellers.
PubMatic’s leadership frames the case as a bid to reopen fair competition. Its CEO has said publicly that the company’s progress hit artificial ceilings created by Google’s market power, not technical limits. Trial testimony in a prior antitrust proceeding indicated Google at one point evaluated acquiring PubMatic before buying the ad tech firm AdMeld instead—an anecdote that underscores how consolidation and vertical integration have defined this sector.
Why the stakes are so high
Digital advertising is a massive market, with internet ad revenues in the United States alone topping hundreds of billions of dollars annually, per the IAB/PwC Internet Advertising Revenue Report. Programmatic trading accounts for the vast majority of display spending, according to eMarketer, meaning even small frictions in auction design or access can redirect large flows of revenue and influence which publishers thrive.
A UK competition regulator’s analysis has previously described Google’s share of publisher ad serving as dominant and highlighted conflicts of interest when the same company runs the leading ad server and a major exchange. Those findings echoed long-running concerns from publishers and rival platforms: when the referee is also a player, neutrality becomes hard to trust, especially in milliseconds-long auctions where transparency is scarce.
If courts ultimately require divestitures—such as separating Google’s ad server from its exchange—or impose conduct remedies like strict interoperability and data firewalls, the mechanics of programmatic auctions could shift materially. That could accelerate independent header bidding, change take rates, and alter how supply-path optimization strategies are executed by agencies and DSPs.
Google’s defense and the broader legal context
Google has consistently denied that its ad tech practices are anti-competitive, arguing its tools create more efficient markets, lower costs, and deliver higher yields for publishers and better performance for advertisers. The company says alternatives to its products are abundant and that features like Open Bidding increased interoperability and reduced latency compared with early header bidding setups.
The PubMatic suit slots into a crowded legal landscape. The U.S. Department of Justice and multiple states have pursued structural remedies against Google’s ad tech stack in federal court. In Europe, the European Commission has advanced a case that contemplates divestiture as a potential fix, and France’s competition authority has previously fined Google over ad server conduct. Private actions from publishers and rival platforms have added parallel pressure, even as some claims have been narrowed or settled.
What to watch next
Key questions now include whether PubMatic’s case will be coordinated with existing federal proceedings, what discovery might surface about exchange mechanics, and how the court will weigh structural versus behavioral remedies. Any ruling that reshapes how Google’s ad server interacts with exchanges would reverberate through fee structures, auction transparency, and the balance of power between walled gardens and the open web.
For publishers, the outcome could influence yields, buyer access, and leverage in negotiations. For advertisers, it could change supply-path strategies and the calculus of working through Google’s stack versus independent routes. For the market as a whole—navigating cookie deprecation, privacy shifts, and AI-driven bidding—the case represents a pivotal test of whether openness and competition can be rebuilt into the core of programmatic advertising.