US Justice Department demands Google break up its ad business over monopoly ruling

The justice department has argued divestment of Google’s ad exchange business is the only way to break up its dominance.

The US Department of Justice (DoJ) is seeking to force Google’s parent company, Alphabet, to divest major parts of its digital advertising business after a federal court found the tech giant had illegally monopolised the online ad market, the Financial Times reported.

In a filing submitted Friday, the DoJ asked Judge Leonie Brinkema to compel Alphabet to sell off its ad exchange and publisher ad server—two central pillars of its dominance in the digital advertising space. The ad exchange operates as the largest marketplace for real-time bidding on digital ad space, while the publisher server is the technology used by websites to manage and display ads.

The Justice Department also urged the court to mandate that Google share real-time bidding data with competitors to level the playing field. A trial to examine the proposals and Alphabet’s objections is set to begin on September 22 in Virginia.

A major antitrust blow for Alphabet

Judge Brinkema ruled last month that Google had “wilfully” monopolized parts of the ad market, finding that the company’s practice of tightly integrating its ad exchange with its publisher server had effectively locked out competitors and allowed it to undercut rivals on pricing. However, the judge dismissed a portion of the DoJ’s case, which alleged that Google also dominated advertiser ad networks unfairly.

Despite the partial win, the ruling marks a significant legal setback for Alphabet—its third major antitrust loss in the US in less than two years. The company continues to reject the monopoly accusations, claiming it competes fiercely with other tech giants like Meta, Amazon, and TikTok for advertising dollars.

Lee-Anne Mulholland, Google’s head of regulatory affairs, slammed the DoJ’s proposed remedies, saying: “The DoJ’s additional proposals to force a divestiture of our ad tech tools go well beyond the court’s findings, have no basis in law, and would harm publishers and advertisers.”

Search and Android under fire too

Alphabet’s mounting legal troubles extend beyond advertising. Last year, a separate ruling found that Google had maintained a monopoly in search by paying Apple more than $20 billion annually to remain the default browser on iPhones and other devices. In that case, the DoJ has proposed that Alphabet be forced to sell Chrome, its dominant web browser, and share search data with rivals.

In court this week, Alphabet CEO Sundar Pichai testified in the search remedies trial, calling the DoJ’s proposals “extraordinary” and warning that forced data sharing would threaten users’ privacy and give rivals a blueprint to reverse-engineer its proprietary systems.

In yet another ruling, a San Francisco judge found that Alphabet had abused its power in the mobile app ecosystem through the Google Play Store, suppressing competition and charging excessive fees. As a result, the company has been ordered to open up Android to competing app stores.

Big Tech under mounting scrutiny

These escalating cases form part of the US government’s broader crackdown on Big Tech’s market dominance. Regulators are increasingly focused on structural remedies—like breakups and mandatory data-sharing—to restore competitive conditions in markets ranging from advertising to app distribution.

While Alphabet continues to appeal the rulings and resist proposed divestitures, the growing legal consensus against its business practices may reshape not just the company’s operations but the very structure of digital advertising in the US.