Google keeps its ad exchange after a judge picks rules over a breakup

On September 2, U.S. District Judge Leonie Brinkema decided what happens to Google after she found it had illegally monopolized parts of online advertising. She said no to a breakup. According to Courthouse News, she rejected the Justice Department’s requests to divest the AdX ad exchange and to open-source the final auction logic of DoubleClick for Publishers (DFP), Google’s publisher ad server. She adopted most of the proposed behavioral remedies “as modified by this court” instead.

Her full reasoning stayed sealed for 14 days. When it came out, it explained a decision that was less about Google’s conduct, which she had already condemned in April 2025, than about what a court can realistically fix in a market that keeps moving.

Why the judge chose rules over a sale

The Current reports that Brinkema called structural remedies “neither realistic nor needed.” She wrote that behavioral remedies would be enough to “effectively pry open to competition” the ad tech markets, and warned that a structural remedy “runs the risk of impairing rather than enhancing competition.” The same report says she compared imposing a remedy on fast-changing ad tech to trying to shoe a galloping horse.

Time also mattered. A full divestiture would have taken several years, The Current reported, while every behavioral remedy is supposed to be fully in effect within 15 months. At the final arguments, Courthouse News notes, the judge acknowledged that Google would likely appeal, which could have stalled any order to sell for a long time. Rules that start in 15 months look different from a sale that might sit in appeals court.

Google’s own argument also landed in the record. It said that selling AdX could push its investment toward other ad formats, which would hurt open-web publishers that depend on its demand. Whether or not the judge accepted that, the outcome is the one Google wanted. Lee-Anne Mulholland, Google’s vice president for regulatory affairs, said the company was “very pleased the court rejected the DOJ’s proposal.” A Justice Department spokesperson said the Antitrust Division was “pleased that the court ordered substantial relief” and was “evaluating appropriate next steps.”

What the rules actually require

The Current groups the behavioral remedies into four buckets:

• Interoperability. Google must connect AdX and DFP to Prebid, the open-source header bidding tool, and let AdX bid in real time on equal terms in rival publisher ad servers.
• Data. Publishers get winning and losing bid data from AdX, portable DFP data for open-web display ads, and documentation explaining how DFP makes auction decisions.
• Non-discrimination. AdX and DFP may not favor Google’s own tools.
• Buy-side limits. Google’s advertiser tool, AdWords, cannot bid directly into DFP or favor Google-owned ad tech on the basis of ownership.

A federal monitor will oversee all of this for six years. Within 30 days of the order, according to Courthouse News, the two sides had to file one jointly proposed final judgment, and if they cannot agree the court may call for more briefing or oral argument. I have not seen a report saying that judgment has been entered, so the exact wording of the obligations may still shift.

Who gains, and the doubts

The clearest winners are publishers with the technical staff to use the new access. Seeing losing bids and DFP’s decision logic is the kind of information that lets a publisher check whether Google’s server was routing money fairly. Digiday’s editors say publishers’ attention has moved to whether the remedies improve interoperability and auction-data access, which could give them more visibility into pricing. The same piece reports that some publishing executives had doubted that moving AdX to another owner would materially improve competition, so the relief on offer may suit them better than the one they did not get.

The doubts are practical. Digiday lists the open questions: how the final judgment will be enforced, whether publishers will actually use more rival infrastructure, and whether Google can comply while keeping advantages that come from its scale and customer relationships. Behavioral remedies depend on someone checking that the rules are followed, and a six-year monitor is a long commitment for a market where, per The Current, Google’s AdWords share of impressions fell from 40% in 2019 to 11% in 2025 as the company leaned on YouTube and AI. By the time rules take full effect, the part of the business they regulate may matter less to Google than it did.

Money is the other thread. Courthouse News says PubMatic sued Google in 2025 seeking more than $1 billion in damages and that rival companies are pursuing damages based on the ruling. The EU separately fined Google about $3.2 billion over the same kind of conduct. For Google, a ruling that keeps the business intact does not end the exposure.

What to watch

Three things decide whether this matters. First, the final judgment text, where the fine print on data access and Prebid integration will be settled. Second, Google’s appeal: it has said it will challenge the liability finding, and the Justice Department has not said whether it will contest the remedy. Third, whether publishers measurably shift traffic to rival exchanges once the 15-month window closes.

For anyone who runs ads on a small site, the practical effect will be slow and indirect, a gradual change in who can bid and how much data is visible, not a switch that flips on one day.