Advertising Data Collaboration Platform Dominance Risks in Europe

1. Introduction

An Advertising Data Collaboration Platform is a digital platform through which advertisers, publishers, agencies, data providers, measurement companies, retailers, and technology firms combine or exchange advertising-related data.

Examples of functions include:

audience matching;

customer segmentation;

conversion measurement;

attribution;

advertising-performance analytics;

identity resolution;

clean rooms;

campaign optimisation;

cross-platform measurement;

sharing of first-party and aggregated data.

The competition-law concern arises when one platform becomes a critical intermediary for advertising data and gains control over data, access conditions, interoperability, measurement, or downstream advertising opportunities.

Importantly, “data collaboration platform dominance” is not itself a separate legal offence. Under EU competition law, the analysis normally asks whether there is a relevant market, whether the undertaking is dominant, and whether its conduct amounts to exclusionary or exploitative abuse under Article 102 TFEU. The EU Digital Markets Act (DMA), GDPR and national competition law may also become relevant.

The issue is particularly important in light of the European Commission's September 2025 Google ad-tech decision. The Commission found Google infringed EU antitrust rules by favouring its own online display advertising technology services and imposed a €2.95 billion fine. (Competition Case Search)

2. Meaning of an Advertising Data Collaboration Platform

A simplified structure is:

Advertiser → Data Collaboration Platform → DSP/Ad Exchange → Publisher

But the platform may also receive information from:

Publisher + Retailer + Agency + Data Provider + Measurement Provider + Advertiser

The platform can therefore occupy a strategically important position between multiple sides of the advertising ecosystem.

Typical data

It may process:

first-party customer data;

advertising-event data;

conversion data;

browsing or engagement information;

contextual data;

purchase information;

audience segments;

campaign-performance data;

measurement data;

aggregated market information.

The greater the number of participants, the more valuable the platform's dataset can become.

This creates a potential data-network effect:

More participants → more data → better matching/measurement → more participants → still more data.

That cycle can create substantial barriers to entry.

3. Why Dominance Can Develop

A. Data accumulation

A platform may combine data from many participants.

A rival starting with a smaller user base may therefore have difficulty matching the incumbent's:

audience coverage;

measurement accuracy;

conversion information;

targeting capability;

historical datasets.

However, possession of large quantities of data does not automatically establish dominance.

The competition authority must examine whether the data provides durable market power and whether competitors can obtain comparable inputs.

B. Network effects

Advertising platforms can have strong indirect network effects.

For example:

More advertisers → more advertising demand → more publishers → more inventory → more advertisers.

At the same time:

More participants → more data → better advertising performance → greater attractiveness.

This can create a reinforcing ecosystem.

C. Switching costs

Advertisers and publishers may invest heavily in:

APIs;

data schemas;

campaign history;

measurement systems;

contracts;

identity infrastructure;

software integrations.

Consequently, switching to another platform may be technically and commercially expensive.

4. Relevant Market Definition

The first major legal question is:

What exactly is the relevant market?

Possible markets include:

advertising-data collaboration services;

advertising measurement services;

audience-management services;

data clean-room services;

identity-resolution services;

publisher-side advertising technology;

advertiser-side advertising technology;

online display advertising;

retail-media data services.

A platform could potentially be dominant in one layer without being dominant across the entire advertising industry.

The Commission's Google ad-tech investigation illustrates the importance of analysing separate layers of the advertising technology chain rather than treating “online advertising” as one undifferentiated market. (Competition Case Search)

5. Dominance Through Data Control

Under Article 102 TFEU, dominance generally involves economic strength allowing an undertaking to behave to an appreciable extent independently of competitors, customers and consumers.

For an advertising-data collaboration platform, relevant indicators may include:

1. Market share

Market share remains relevant but is not decisive.

2. Data advantage

Questions include:

Is the data unique?

Is it difficult to reproduce?

Is it updated continuously?

Is it commercially necessary?

Can rivals purchase equivalent data?

3. Network effects

A larger platform may provide better results because it has more participants.

4. Entry barriers

Potential barriers include:

data acquisition;

technical integration;

customer acquisition;

interoperability;

regulatory compliance;

trust;

measurement standards.

5. Switching costs

The authority may investigate whether customers can realistically migrate to competitors.

6. Major Dominance Risks

A. Self-preferencing

A dominant platform may use its data advantage to favour its own advertising services.

For example:

Platform owns the data collaboration infrastructure + owns an advertising exchange + owns an advertising-buying tool.

It might allegedly provide its own advertising business with better access, faster data, superior measurement or preferential ranking.

The Google Shopping judgment is important by analogy. In Google and Alphabet v Commission, C-48/22 P, the Court of Justice upheld the finding concerning Google's preferential treatment of its own comparison-shopping service. The Court dealt with capability of foreclosure, effects and the relationship between dominant-market power and conduct on a related market. (curia)

Application

A similar analytical question could arise if a dominant advertising-data platform:

gives its own DSP privileged data access;

gives its own ad exchange superior information;

limits competitors' access;

gives its own advertising services better measurement tools.

7. Data Siloing

A dominant platform could theoretically make important advertising data available internally but deny equivalent access to independent competitors.

For example:

Platform's advertising division: complete conversion information

Independent DSP: incomplete conversion information

This can produce a competitive advantage.

The legal question is not simply whether information is withheld. The question is whether the information is sufficiently important and whether the refusal or discriminatory access has exclusionary effects.

8. Refusal of Access

The Bronner doctrine is important here.

Case 1 — Oscar Bronner GmbH & Co KG v Mediaprint

C-7/97, Court of Justice, 26 November 1998

The case concerned access to a newspaper home-delivery system.

The Court established a strict framework for treating refusal to supply or provide access to infrastructure as abusive.

The essential-facilities reasoning is relevant by analogy to an advertising-data platform.

A claimant would generally need to establish particularly strong circumstances, including that the input is indispensable and that duplication is not realistically possible.

Advertising application

A rival might argue:

“The dominant advertising-data platform controls an indispensable dataset and without access we cannot compete.”

But mere usefulness or commercial attractiveness would not automatically satisfy the strict legal test.

9. Data Interoperability and Indispensability

Case 2 — IMS Health GmbH & Co OHG v NDC Health GmbH & Co KG

C-418/01, Court of Justice, 29 April 2004

IMS Health concerned refusal to license a pharmaceutical-sales data structure.

The Court developed important principles concerning refusal to license intellectual property and access to an indispensable input.

The case is particularly useful for advertising-data collaboration because the dispute involved a structured information system that could be important for downstream competition.

Relevance

An advertising-data platform could face scrutiny if:

its data structure is indispensable;

rivals cannot realistically reproduce it;

access is denied;

downstream competition is eliminated;

access would enable a new product or service;

there is no adequate objective justification.

Again, IMS Health is an analogy rather than a direct advertising-data precedent.

10. Data + GDPR + Competition Law

One of the most important modern cases is:

Case 3 — Meta Platforms and Others v Bundeskartellamt

C-252/21, Court of Justice, 4 July 2023

Meta collected data from Facebook users and combined it with information from other Meta services and third-party websites/apps.

The Court held that a national competition authority may, when assessing abuse of dominance, consider whether processing of personal data complies with the GDPR, while respecting the powers and cooperation requirements involving data-protection authorities. (curia)

Advertising significance

This is highly relevant to advertising-data collaboration.

A platform's competitive advantage may arise from:

social-network data + third-party data + advertising data + behavioural data.

Competition law can therefore intersect with privacy law.

This creates a major risk where:

Data concentration itself becomes part of the mechanism through which market power is exercised.

11. Data Combination as a Competitive Advantage

Suppose Platform A possesses:

advertising data;

shopping data;

publisher data;

measurement data;

audience data.

It combines them to create highly detailed advertising profiles.

Platform B cannot obtain comparable information.

The competition authority could investigate whether this combination creates:

barriers to entry;

exclusionary effects;

customer lock-in;

discriminatory access;

reduced innovation.

The Commission has specifically considered the competitive effects of data combination in its analysis of online advertising markets. (European Commission)

12. Discriminatory Access

A dominant platform might offer:

Such differences are not automatically unlawful.

The legal analysis would ask:

Are the businesses similarly situated?

Is there a legitimate reason for different treatment?

Does the discrimination disadvantage competitors?

Does it affect competition?

Does it strengthen dominance?

13. Margin Squeeze

A platform may control an upstream data service while competing downstream.

For example:

Upstream: advertising-data collaboration service

Downstream: advertising optimisation

The platform might charge competitors high prices for the data service while offering its own downstream business favourable internal terms.

This can create a margin-squeeze theory.

Case 4 — Deutsche Telekom v Commission

C-280/08 P, Court of Justice, 14 October 2010

The Court dealt with margin squeeze involving a vertically integrated dominant undertaking.

The principle is relevant to advertising-data ecosystems because a vertically integrated platform may operate at several levels and potentially use conditions at one level to disadvantage rivals at another.

Advertising example

Data platform → DSP → advertiser

If the same company controls both the data input and downstream advertising service, competition authorities may examine whether its pricing/access conditions make equally efficient rivals unable to compete.

14. Selective Pricing and Discounts

Advertising-data platforms may provide:

volume discounts;

loyalty rebates;

data-access discounts;

bundled services;

free analytics;

preferential fees.

These arrangements can become problematic where they have exclusionary effects.

Case 5 — Post Danmark v Konkurrencerådet

C-209/10, Court of Justice, 27 March 2012

The Court considered selectively low prices and price discrimination by a dominant undertaking.

The Court stressed that price discrimination does not automatically constitute exclusionary abuse; the effects on competition and possible objective justification matter. (Infocuria)

Advertising application

A platform offering advertisers:

“Use our data collaboration system exclusively and receive much cheaper measurement.”

could raise questions if the arrangement materially disadvantages competing platforms.

15. Leveraging

A dominant undertaking in one market may use that position to strengthen itself in another market.

This is particularly relevant to advertising data.

Example:

Dominant data platform

↓

controls audience data

↓

uses data advantage

↓

enters measurement market

↓

forecloses independent measurement providers

This is called leveraging.

16. Google Shopping as a Modern Analogy

Case 6 — Google and Alphabet v Commission

C-48/22 P, Court of Justice, 10 September 2024

The Court upheld the €2.4 billion fine concerning Google's favouring of its own comparison-shopping service.

The judgment discusses:

dominance;

self-preferencing;

leveraging;

foreclosure;

potential effects;

causation;

competition on the merits.

(curia)

Advertising-data relevance

The case provides a useful framework for analysing situations where:

A dominant platform controls an important gateway and gives its own downstream service preferential treatment.

It is not an advertising-data case, but its reasoning is highly relevant by analogy.

17. Google AdSense

Case 7 — Google AdSense

European Commission, AT.40411, decision of 20 March 2019

The Commission investigated Google's conduct in online search advertising intermediation.

The case concerned contractual restrictions affecting publishers using Google's AdSense service.

It is especially relevant because it directly concerns the advertising ecosystem.

The broader lesson is that contractual restrictions imposed by an important advertising intermediary can be examined under Article 102 TFEU when they restrict competing advertising intermediation.

18. Google's 2025 Ad-Tech Decision

Case 8 — Google Ad-Tech and Data-Related Practices

European Commission, AT.40670, decision of 5 September 2025

This is particularly important for the topic.

The Commission's case concerns Google's advertising-technology practices and was brought under Article 102 TFEU and Article 54 EEA. The decision was adopted on 5 September 2025. (Competition Case Search)

The Commission found Google favoured its own online display advertising technology services to the detriment of competing ad-tech providers, advertisers and publishers and imposed a €2.95 billion fine, together with remedial measures concerning self-preferencing and conflicts of interest along the ad-tech supply chain. (Digital Markets Act (DMA))

Importance

This is the closest major modern EU competition-law authority for advertising-data collaboration risks.

It demonstrates that authorities can examine the whole technological chain, rather than merely looking at a traditional single-product market.

19. DMA Dimension

The Digital Markets Act creates an additional layer of regulation.

The DMA contains advertising-related obligations affecting designated gatekeepers.

For example, Article 6(8) requires a gatekeeper, upon request, to provide advertisers and publishers, and authorised third parties, access to performance-measuring tools and the data necessary for independent verification of advertising inventory. (Digital Markets Act (DMA))

This is important because independent measurement can reduce information asymmetry.

Competition-law significance

A platform should not necessarily be able to say:

“Trust our own advertising measurement.”

The regulatory approach increasingly supports independent verification.

20. Potential Abuse Categories

An advertising-data collaboration platform may face several competition-law theories.

21. Algorithmic Discrimination

A platform may claim:

“Our algorithm treats everyone equally.”

But the actual algorithm might provide different data access or ranking to different participants.

For example:

Own DSP: real-time conversion data

Rival DSP: delayed conversion data

Even if contracts appear formally identical, technological implementation may produce unequal competitive conditions.

Evidence may therefore include:

API logs;

auction logs;

access timestamps;

data-field availability;

algorithmic rules;

ranking systems;

internal communications;

A/B testing;

historical performance data.

22. Data Exclusivity

An advertising platform might require:

“All customer advertising data must be supplied exclusively to us.”

Such clauses are not automatically illegal.

But competition authorities may examine:

duration;

market coverage;

market power;

importance of the data;

availability of alternatives;

foreclosure percentage;

switching possibilities.

The issue becomes more serious where the platform already has significant market power.

23. Tying and Bundling

A platform might offer:

Data collaboration + measurement + DSP + ad exchange

only as one package.

A competitor specialising in measurement may therefore be unable to compete independently.

The legal analysis could involve:

separate products;

dominance in the tying product;

coercion or practical bundling;

foreclosure;

objective justification;

consumer effects.

24. Essential Data Problem

One of the hardest questions is:

When does advertising data become legally indispensable?

Not every valuable dataset is an essential facility.

The analysis should examine:

uniqueness;

replicability;

cost of duplication;

time needed to reproduce it;

alternative sources;

interoperability;

downstream competitive importance.

The strict reasoning in Bronner and IMS Health makes this area particularly demanding.

25. Privacy as a Competition Parameter

Advertising-data platforms create an important intersection between:

Competition law + GDPR + consumer protection + DMA.

Privacy may affect competition because different platforms may compete on:

data collection;

data minimisation;

consent mechanisms;

tracking;

personalisation;

cross-service data combination.

The Meta C-252/21 judgment demonstrates that data-protection legality can become relevant in a competition-law assessment of a dominant platform. (Infocuria)

26. Civil-Law and Private Enforcement Consequences

Competition-law problems can generate private disputes.

Potential claimants include:

Advertisers

They may allege:

excessive fees;

discriminatory treatment;

loss caused by distorted auctions;

incorrect measurement.

Publishers

They may allege:

discriminatory access;

unfair contractual terms;

reduced advertising revenue;

restrictive technology arrangements.

Competitors

They may allege:

exclusion;

refusal of access;

discriminatory data treatment;

foreclosure.

Consumers

Consumer claims may arise where competition restrictions combine with:

privacy violations;

misleading advertising;

unfair commercial practices.

27. Causation and Damages

A claimant generally needs to establish more than:

“The platform was dominant.”

The important chain is:

Dominance → abusive conduct → restriction of competition → claimant harm → causal connection → quantifiable damage.

Possible damages may include:

lost revenue;

excess advertising expenditure;

lost customers;

reduced publisher income;

lost market share;

overcharges.

Economic evidence is often crucial.

28. Six Core Cases for Examination

Additional highly relevant authority: Google AdSense, AT.40411, and the Google Ad-Tech and Data-Related Practices decision, AT.40670. The latter is a Commission decision rather than judicial “case law” in the strict sense. (Competition Case Search)

29. Direct vs Analogical Authorities

This distinction is important for legal writing.

More directly related to advertising technology

Google Ad-Tech, AT.40670

Google AdSense, AT.40411

Meta Platforms, C-252/21

Mainly analogical competition authorities

Google Shopping, C-48/22 P

Bronner, C-7/97

IMS Health, C-418/01

Deutsche Telekom, C-280/08 P

Post Danmark, C-209/10

Therefore, it would be incorrect to say that all eight cases directly concern advertising-data collaboration platforms.

30. Key Legal Test

A useful examination framework is:

Step 1 — Define the market

What advertising-data or advertising-technology service is involved?

Step 2 — Establish dominance

Look at:

market share;

data advantage;

network effects;

entry barriers;

switching costs;

customer dependency.

Step 3 — Identify conduct

Was there:

self-preferencing?

discriminatory access?

tying?

exclusivity?

refusal to supply?

margin squeeze?

data exploitation?

Step 4 — Establish effects

Could the conduct:

exclude competitors;

prevent entry;

reduce innovation;

increase dependency;

distort advertising markets?

Step 5 — Consider justification

Could the conduct be objectively necessary or produce efficiencies benefiting consumers?

Step 6 — Consider other regimes

Also examine:

GDPR;

DMA;

consumer protection law;

national competition law;

contractual law;

damages actions.

31. Simple Example

Suppose AdDataCo operates a dominant advertising-data collaboration platform.

It receives data from 10,000 advertisers and publishers.

AdDataCo also owns a DSP.

It then:

gives its DSP immediate access to conversion data;

gives rival DSPs delayed data;

charges rivals higher data-access fees;

requires publishers to use AdDataCo exclusively;

combines all data to improve its own advertising predictions.

The legal questions become:

Market:
Is AdDataCo dominant in advertising-data collaboration?

Conduct:
Is there discriminatory access or self-preferencing?

Effects:
Are rival DSPs being foreclosed?

Data:
Is the dataset difficult or impossible to reproduce?

Privacy:
Is the data combination GDPR-compliant?

DMA:
Does a gatekeeper obligation apply?

Remedy:
Would access, interoperability, behavioural restrictions or other measures be appropriate?

32. Important Distinction

Data concentration ≠ dominance

Having enormous data does not automatically mean an undertaking is dominant.

Dominance ≠ abuse

A dominant undertaking is not prohibited from competing aggressively.

Vertical integration ≠ illegality

Owning multiple advertising services is not itself unlawful.

Data advantage ≠ essential facility

The data must satisfy the demanding legal conditions before a refusal-to-access theory succeeds.

Privacy violation ≠ automatic competition infringement

The competition analysis still requires the relevant Article 102 framework, although GDPR issues may be relevant to that assessment.

33. Overall Legal Structure

The topic can therefore be represented as:

Advertising Data Collaboration Platform

↓

Data aggregation

↓

Network effects

↓

Data advantage

↓

Customer dependency

↓

Potential dominance

↓

Self-preferencing / exclusion / discriminatory access / tying / exclusivity

↓

Potential foreclosure

↓

Article 102 TFEU + DMA + GDPR

↓

Administrative enforcement + private damages + injunctive remedies

The European Commission's 2025 Google ad-tech decision demonstrates that these issues are no longer purely theoretical: the Commission has specifically examined conflicts of interest and preferential treatment across the ad-tech supply chain. (Competition Case Search)

34. Conclusion

Advertising Data Collaboration Platform Dominance Risks arise when control over a central data-intermediation platform allows an undertaking to obtain or reinforce market power through data accumulation, network effects, interoperability control, switching costs and vertical integration.

The principal European competition-law risks are:

self-preferencing;

discriminatory data access;

exclusionary contracts;

data exclusivity;

tying and bundling;

refusal to provide indispensable data;

margin squeeze;

leveraging;

manipulation of measurement;

discriminatory algorithms;

restrictive interoperability.

The most important modern authority is the 2025 Google ad-tech decision, while Meta C-252/21, Google Shopping C-48/22 P, Bronner, IMS Health, Deutsche Telekom and Post Danmark provide the major judicial principles needed to analyse data-driven advertising dominance. (Competition Case Search)

Exam formula

Advertising Data Platform Dominance = Relevant Market + Data Advantage + Network Effects + Entry/ Switching Barriers + Dominance + Exclusionary Conduct + Foreclosure/Competitive Effects + Article 102 TFEU + DMA/GDPR Interaction + Objective Justification + Remedies.