The EC further pushes to rein-in Google’s ad tech monopoly

Overall, investigators concluded that Google’s vertically integrated ad tech stack created enduring structural conflicts of interest that enabled exclusionary conduct and could not be remedied by competition on the merits alone. See list below for a summary of the EC’s findings. 

Google Ads

Google Ads preferentially routed advertiser demand through AdX, even where this was not in advertisers’ interests, to strengthen AdX’s position in the SSP market.

DV 360 

Google’s DSP DV 360 systematically reduced bids submitted to rival supply-side platforms and adjusted bidding behavior to discourage header bidding and divert demand toward AdX.

AdX

Google’s SSP/ad exchange was artificially advantaged through coordinated buy-side and sell-side practices that increased its auction wins, scale and revenues at the expense of competing SSPs.

DFP 

Investigators found that Google leveraged the dominance of its publisher-side ad server to favor AdX through auction design and execution choices that rival SSPs could not replicate, therefore negatively impacting publishers.

Waterfall auction configuration

The Commission found that legacy waterfall mechanics within DFP prioritised AdX demand and reinforced its preferential access to publisher inventory.

Header bidding integrations

Google implemented technical and economic measures that disadvantaged header bidding solutions relative to AdX, weakening their ability to constrain Google’s exchange.

Open Bidding

Open Bidding preserved AdX’s informational and competitive advantages and did not create a genuinely level playing field for rival SSPs.

Unified Pricing Rules 

The Commission found that UPR eliminated publishers’ ability to set differentiated price floors, limiting competition between demand sources and reinforcing AdX’s competitive position.

First look/Last look 

Using these mechanisms, Google allowed AdX to observe or react to rival bids in ways unavailable to competitors, distorting auction outcomes.

Data advantages

Google exploited tight integration and data advantages across its ad buying tools, ad server and exchange to extend dominance from one layer of the stack into others.

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The European Union’s executive body concluded, stating the above actions breached antitrust rules in the region, standing by its September decision to fine Google €2.95 billion ($3.4 billion) for the conduct. It further stated that Google must end self-preferencing and fix conflicts of interest by implementing new measures. 

The EC further raised the prospect of potentially forcing Google to sell parts of its ad tech business to ensure compliance with its antitrust laws – it’s also worth noting that Google submitted an earlier compliance plan, consisting primarily of behavioral remedies, in November last year.

In a statement shared with Digiday, a spokesperson for the EC stated, “In September 2025, the Commission fined Google €2.95 billion over abusive practices in online advertising and ordered the company to take measures to end the ongoing practices and remove its structural conflicts of interest on the ‘adtech stack’. Today, we have published a provisional non-confidential version of this decision on our website, as required by EU law.”

For its part, Google has already kicked off appeal proceedings in a 17-point defense of GAM, claiming the EC “errs in its assessments of market definition and dominance,” and that the conclusions over its ad tech practices were also in error. The case continues, although Digiday was unable to ascertain the projected timeline of its development. 

The developments come as similar proceedings take place across the Atlantic in the U.S., where Justice Leonie Brinkema is expected to deliver her verdict on Google’s ad tech stack in the coming weeks, where the prospect of forced divestiture is also on the table.