A Reckoning for Google: What the Federal Antitrust Ruling Means for the Future of Ad Tech

A Historic Decision in the Ongoing Fight for Fairness in Digital Advertising

Back in November, we asked the question: What Happens if the Government Breaks Up Google’s DoubleClick? Now, we’re one step closer to finding out.

On April 17, 2025, a federal court ruled that Google violated U.S. antitrust laws by maintaining illegal monopolies in two core areas of the digital advertising ecosystem: publisher ad servers and ad exchanges.

The decision, delivered by U.S. District Judge Leonie Brinkema in the Eastern District of Virginia, concluded that Google “willfully engaged in a series of anticompetitive acts” to acquire and maintain monopoly power in the open-web display advertising market. It’s a significant development with potential long-term implications for advertisers, publishers, platforms and consumers alike.

The full court ruling is available here.

What the Court Found: Tying, Market Dominance and Competitive Harm

According to the decision, Google unlawfully tied its publisher ad server (DFP) to its ad exchange (AdX), forcing publishers who wanted access to high-demand inventory from AdX to also adopt DFP. The court found that this practice excluded competition and harmed both publisher customers and the broader ad tech ecosystem.

“This exclusionary conduct substantially harmed Google’s publisher customers, the competitive process, and, ultimately, consumers of information on the open web.“
— U.S. District Judge Leonie Brinkema

The court further explained that Google:

• Used “First Look” and “Last Look” auction advantages to undercut competitors
  • The court found that Google employed auction mechanisms like “First Look” and “Last Look” to give its own exchange, AdX, preferential treatment. These practices allowed AdX to win auctions even when other exchanges submitted higher bids, thereby disadvantaging competitors and harming publishers.
  • Reference: Pages 29–31 and 99–100 of the court ruling
    
• Removed features that would have allowed publishers to monetize more flexibly
  • The ruling highlighted that Google changed certain product features—such as dynamic pricing controls and real-time bidding access for non-Google ad servers—that would have enabled publishers to monetize their content more effectively. These limitations further entrenched Google’s monopoly power and reduced publisher flexibility.
  • Reference: Pages 76, 97–98, and 110–111
    
• Maintained over 90% market share in publisher ad servers and a dominant position in ad exchanges
  • The court determined that Google held a 91–93.5% global market share in the publisher ad servers market for open web display advertising  between 2018–2022, and  a dominant share in the “open web display transactions” ad exchanges (63–71%), far outpacing its next closest rival at just 6%
  • Reference: Pages 73–74 (publisher ad servers) and 82–83 (ad exchanges)

A Pattern of Monopoly Behavior

This ruling marks the second major antitrust loss for Google in less than a year. In 2024, a separate decision found the company had illegally maintained a monopoly in the search advertising market. That case also opened the door to structural remedies.

According to Reuters, the Department of Justice and 17 states have asked the court to consider breaking up Google’s advertising business, including the potential divestiture of its Google Ad Manager suite.

Axios reported that the business at stake accounts for an estimated 12% of parent company Alphabet’s revenue.

Chris Vanderhook: A Call for Accountability and Change

Viant’s Co-Founder and COO, Chris Vanderhook, responded to the ruling by emphasizing the broader implications for marketers and the digital advertising ecosystem:

“The DOJ’s case against Google is a wake-up call. But it needs to go further—not just to remedy Google’s abuse of power, but to prevent the next wave of it.”

Chris also addressed the misalignment between vertically integrated media sellers and the marketers they claim to serve:

“Smart marketers are moving to buy-side-only DSPs with no media to sell, no conflicts of interest, and aligned incentives. If your DSP represents both sides of the deal, you’re not the customer—you’re the target.”

Why This Matters for Advertisers and Publishers

This decision reinforces a key principle in antitrust enforcement: Monopolies are not illegal—but monopolistic conduct is.

Google’s practices went beyond dominance. The court found that it used its market position to exclude competition, manipulate auction dynamics, and limit publisher choice—all while preserving its own share and undermining transparency.

For advertisers, this is a moment to reexamine who represents their interests—and how media dollars are managed across the supply chain.

For publishers, the decision could mark a turning point in restoring revenue and autonomy in the open web.

What’s Next: A More Transparent Ecosystem Starts Here

As remedies are determined and legal appeals unfold, one thing is clear: programmatic advertising is entering a new era of accountability.

At Viant, we’ve long been building for that future. Our buy-side-only DSP is built from the ground up to put marketers first—no media to sell, no conflicts of interest, and no black boxes.

We deliver a total platform solution that includes:

• ViantAI™, our next-generation AI engine powering smarter, faster, more effective media buying decisions
  
• An Omnichannel DSP enabling people-based targeting and execution across CTV, digital audio, mobile, display, DOOH, and in-game environments
  
• Direct Access to premium inventory through transparent integrations with leading publishers
  
• Viant Household ID™ Technology, our patented cookieless identity solution that enables precise, people-based marketing
  
• Advanced measurement and attribution, including log-level insights and industry-leading data partner integrations, to understand the true impact of your media spend
  

Our belief is simple: marketers deserve transparency, control, and proof of performance. And we’re proud to offer the tools to make that possible—today.

Final Word

The court’s ruling signals a shift in digital advertising—away from opaque, vertically integrated stacks, and toward platforms that prioritize transparency, fairness and aligned incentives.

Marketers and publishers have a choice in how they move forward.

We’re ready to help lead the way.