Competition in digital advertising markets


Digital advertising is now the leading form of advertising in most if not all OECD countries and offers businesses the ability to reach consumers in ways that could only have been imagined previously. Increased Internet coverage and mobile phone penetration have fundamentally changed the ability of advertisers to reach a broad range of consumers at almost any time of the day and in any context through digital advertising. In addition, developments in artificial intelligence (AI) and machine learning, coupled with the stores of personal data available online, have allowed for cost-effective targeted advertising at scale. Such advertising is traded electronically in real-time across a complex supply chain, sometimes involving numerous actors.

Recent market studies by various competition authorities have highlighted potential competition concerns in digital advertising markets. In particular, there appears to be increasing market concentration and integration across many levels of the supply chain. While some consolidation may reflect underlying network effects and economies of scale in these markets, previous mergers may have exacerbated this. Further, there are concerns that some players have achieved dominance by behaving contrary to competition laws.

In November 2020, the OECD held a roundtable on these issues to:

  • Better understand how digital advertising markets work
  • Assess the state of competition in digital advertising markets
  • Identify what regulatory responses are being considered to address competition concerns in these markets.

This page contains all related documentation.



Best Practice Competition Roundtables 

OECD Handbook on Competition Policy in the Digital Age 

competition in digital advertising markets


Invited speakers

Fiona M. Scott Morton Bio 

Theodore Nierenberg Professor of Economics, Yale Scholl of Management

David Evans Bio ‌  

Chairman, Global Economics Group

Hal Varian Bio  

Chief Economist, Google


Competition in Digital Advertising Markets Cover‌ 

OECD Background note / French version

Executive Summary with key findings

Detailed Summary of the discussion

Contributions from delegations







United Kingdom


Summaries of Contributions 



Fiona Scott Morton on competitive harms that may occur in digital advertising markets

David Evans describes the economics of attention markets and implications for competition

Hal Varian describes search and display advertising, behavioural targeting, and the role of data



Consumer Data Rights and Competition (2020)

Quality Considerations in the Zero-price Economy (2018)

Non-price Effects of Mergers (2018)

Implications of e-Commerce for Competition Policy (2018)

Rethinking the Use of Traditional Antitrust Enforcement Tools in Multi-sided Markets (2017)


OECD Handbook on Competition Policy in the Digital Age 

Recommendation on Consumer Protection in E-Commerce (2016)

Good practice guide on online advertising (2019)

Good practice guide on consumer data (2019)

Online Advertising: Trends, Benefits and Risks for Consumers (2019)

OECD best practice roundtables on competition

More OECD work on competition


Related Documents