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When a publisher first activates Google advertising, it rarely feels like a decision that will shape the next decade.
The ad appears. The revenue enters the report. Nobody has to call every advertiser individually or negotiate a separate campaign for each available space.
Eventually, the arrangement becomes infrastructure.
That is when changing it stops being a matter of replacing one line of code.
AdSense, DFP and AdX are related—but not identical
For many small websites, the Google advertising relationship begins with AdSense, which places ads and shares the resulting revenue with the publisher.
Larger or more complex publishers may use Google Ad Manager. One component of that system is the publisher ad server formerly known as DoubleClick for Publishers, or DFP. It decides which advertisement should fill an available space on a website.
AdX performs a different function. It is an advertising exchange where buyers compete for publishers’ inventory in real-time auctions.
Google owns both products.
The connection matters because the company also controls a major source of advertiser demand through Google Ads, previously called AdWords. A publisher choosing a different ad server or exchange risks losing access to part of that demand.
What looks like a collection of convenient tools can therefore become a tightly connected commercial system.
What the court found Google had done illegally
In April 2025, Judge Leonie Brinkema of the U.S. District Court for the Eastern District of Virginia found that Google had unlawfully acquired and maintained monopoly power in two markets for open-web display advertising:
- publisher ad servers;
- advertising exchanges.
The court found that Google had tied DFP and AdX together through contracts and technological integration. Publishers that wanted real-time access to demand from Google’s advertiser network were pushed toward using both Google products.
According to the court’s findings, Google also used policies and auction features that gave AdX advantages over competing exchanges.
By 2022, DFP served approximately 91% of open-web display impressions in the worldwide publisher ad-server market. AdX processed a majority of transactions among the exchanges that produced data for the litigation.
The court also found that Google had maintained a 20% AdX fee even as competing exchanges often charged closer to 10%. Publishers generally did not leave because access to Google’s advertising demand left them with limited practical alternatives.
That is the central antitrust problem.
The tools were not dominant only because publishers liked them. Google had designed the surrounding market in ways that made choosing a competitor economically difficult.
The Justice Department asked the court to separate the stack
After winning the liability phase, the Justice Department proposed structural remedies.
Google would have been required to sell AdX to an approved buyer. The company would also have had to open-source the final auction logic inside DFP. Under certain conditions, the remaining DFP business could have been sold later.
On September 2, 2026, the court rejected those structural remedies.
The judge did not reverse the earlier monopoly findings. She concluded that the proposed breakup was not a realistic or necessary way to restore competition when less disruptive behavioral remedies were available.
The evidence showed how deeply AdX depends on Google’s broader technical infrastructure. The government’s proposed schedule allowed as many as 540 days to migrate AdX to a buyer, followed by up to two additional years for customer migration. Identifying and approving a buyer would add more time.
Previous technology migrations described during the trial had taken even longer. Moving DoubleClick onto Google’s infrastructure took seven years. Replacing one dependency shared by AdX and DFP took five years and involved approximately 40 engineers.
The scale is equally difficult to separate. According to testimony from a Google engineering director, Google Ad Manager processes approximately 8.2 million ad requests and 60 million bid requests every second at peak.
A failed or degraded migration would not inconvenience publishers in the abstract. It could interrupt the system responsible for filling advertising space and producing revenue across thousands of websites.
The judge also found commercial uncertainty. The government had not identified a buyer clearly capable of acquiring AdX and reproducing its functionality at the required scale.
The breakup was rejected because the court considered it technically risky, commercially uncertain and broader than necessary—not because Google’s conduct had become lawful.
What Google must change instead
The tools will remain under Google’s ownership, but the ruling does not leave the existing arrangement untouched.
The court selected behavioral remedies intended to loosen the connection between Google’s products and lower the cost of choosing competitors.
According to the Justice Department’s description of the relief, Google will be required to:
- integrate AdX and DFP with Prebid, an open-source header-bidding system;
- allow AdX to submit real-time bids through competing publisher ad servers;
- let publishers access and export historical and configuration data from DFP;
- provide ongoing AdX bidding data, including winning and losing bids;
- prevent Google Ads from bidding preferentially into Google-owned tools;
- operate under a court-appointed monitor and technical committee for six years.
The Prebid integrations are especially important.
Instead of allowing DFP’s final auction to remain the invisible decision-maker, publishers may be able to run more of the competition through an auction whose logs and mechanics they can inspect.
Data portability addresses another source of dependence. A publisher that can export campaign settings, historical records and bidding information has a better chance of testing or adopting another ad server without rebuilding everything from the beginning.
These remedies do not create a competitive market overnight. They are designed to give competitors and publishers a better route into one.
Lock-in is measured by the cost of leaving
The case offers publishers a practical definition of vendor lock-in.
You are locked in when changing providers would require so much time, lost revenue, technical work and operational risk that staying becomes the only realistic choice.
The warning signs are not always visible when a system is first installed. They appear years later when the newsroom asks basic questions:
- Who controls our advertising accounts and historical data?
- Can we export our campaign settings in a usable format?
- Which demand sources disappear if we change ad servers?
- Who owns the relationships with our advertisers?
- How many tags, templates and consent settings would have to be rebuilt?
- Can we test another provider alongside the current system?
- How long could the site operate if the migration interrupted ad delivery?
- Does anyone in the organization still understand why the stack was configured this way?
If nobody can answer without calling the incumbent provider, the dependency is already part of the business model.
Publishers do not need to leave Google tomorrow
The lesson is not that every local newspaper should immediately remove Google advertising.
For many publishers, programmatic demand remains useful. A rushed migration can lose revenue, break reporting and create more operational risk than it removes.
The practical goal is optionality.
A publisher can maintain programmatic advertising while strengthening revenue streams it controls more directly. That includes locally sold campaigns, sponsorships, contextual placements, newsletter advertising, events and business services.
CMS4media, for example, supports multiple publisher-controlled advertising formats, including standard banners, contextual ads, website backgrounds, pop-ups, video and audio advertising. It can also accept external advertising code.
Those tools do not reproduce the scale of AdX, and they should not be described as a complete replacement for a global exchange.
They create a second path.
A campaign sold directly to a local hospital, dealership or contractor belongs to a relationship the publisher controls. The newsroom knows the advertiser, the price, the placement and the duration. That revenue does not disappear because an external auction changes its rules.
Build the exit before you need it
The court’s ruling exposes a difficult paradox.
Google’s products became so interconnected and important that dismantling them risked harming the same publishers the antitrust case was meant to protect.
That does not make the monopoly harmless. It demonstrates the cost of allowing dependence to accumulate for years before asking how the system could be separated.
Publishers cannot rewrite the advertising market by themselves. They can reduce their own exposure.
Document the current stack. Export the data that can be exported. Preserve direct advertiser relationships. Test additional demand sources. Make sure the website can support advertising that the publisher sells and controls.
The most useful question is not whether the newsroom could abandon Google next Monday.
It is whether the publisher is building enough alternatives to have a meaningful choice next year.
