Why the US DOJ wants to break up Google’s ad business and what it means
The court’s finding that Google illegally monopolized parts of the ad stack now puts structural fixes, including a possible breakup, on the table.
The US Department of Justice (DOJ) had already won a major antitrust victory against Google’s advertising business. In an April 2025 ruling, Judge Leonie Brinkema found that Google unlawfully monopolized two critical layers of the open web’s ad stack: the publisher ad server market and the ad exchange market.
This ruling placed the case into the remedies phase, where the court is now deciding how to fix the harm caused by Google’s conduct. The DOJ is urging the court to impose structural changes. Its lawyers argue that Google’s dominance across the ad tech stack cannot be addressed with promises or fines. They want the company to sell AdX, the exchange where publishers pay a fee for real time display ad auctions, and to open key auction technology to the public.
Regulators say Google’s influence stretches from the tools publishers use to sell ads to the exchange where trades occur, supported by strong advertiser demand. They describe this as the equivalent of a single financial firm owning Goldman Sachs and the New York Stock Exchange.
Oyinebiladou Omemu
Google, of course, argues that a breakup would be technically disruptive and harmful to the publishers and advertisers who depend on its systems. The company says targeted behavioral commitments and increased transparency would be less damaging. Judge Brinkema has pressed both sides on the feasibility of any forced divestiture. She noted that Google is likely to appeal a structural remedy, which could delay any breakup for years, and raised concerns about how such a remedy would be enforced during an appeal.
The case also forms part of a wider effort in the United States to reduce the dominance of large technology companies such as Apple, Amazon and Meta. A similar push to restructure Google Search monopoly in 2024 did not succeed, and courts have rejected previous attempts to break up Meta's WhatsApp and Instagram.
Even so, the DOJ maintains that Google’s role in advertising is uniquely concentrated. Internal estimates show that about 46% of indirect open web display ad spend flows through Google’s systems, giving the company significant influence over how online ads are bought and sold.
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The implications of this case extend beyond the United States. Google’s ad tools underpin digital marketing for businesses around the world. Any forced divestiture could reshape how online content is monetized globally. Emerging markets, including many across Africa and Asia, rely heavily on Google ads for media revenue and small business growth.
A breakup could create room for local ad tech competitors and reduce dependence on a single global provider, although short term disruption in ad delivery and measurement is likely in regions where infrastructure is still developing.
The takeaway
If the court orders structural changes, it would represent a significant shift in global digital advertising. Emerging markets may benefit from new competition and innovation, while international brands face a more fragmented ad landscape. For Google, the case shows that regulatory scrutiny is growing and that dominance in core markets no longer guarantees long term stability, even for a company that supports much of the world’s online economy.
Oyinebiladou Omemu
