Market concentration


Market concentration measures the extent to which market shares are concentrated between a small number of firms. It is often taken as a proxy for the intensity of competition. Indeed, in recent years changes in concentration have increasingly been used to argue that the intensity of competition is falling, that the growth of large firms with high market shares is driving up profits, damaging innovation and productivity, and increasing inequality. Some have argued that the competition rules need to be rewritten and a crackdown by overly antitrust agencies is required. 

The simplicity of this framing has found supporters across the political spectrum. But does it survive scrutiny? Has concentration increased in OECD countries? How is concentration measured? Does fewer competitors necessarily mean less intense competition? What has the impact of any change in concentration been? What might be driving these changes? and what (if anything) should competition agencies do about it?

In June 2018, the OECD heard from a range of experts during a discussion that explored whether fewer competitors necessarily means less competition. 



OECD Handbook on Competition Policy in the Digital Age

Full list of Competition Policy Roundtables


Key papers and invited speakers information

OECD Issues Paper

Executive Summary with key findings • Synthèse des points clés de la discussion

Detailed Summary of the discussion • Compte rendu detaillé de la discussion 


Notes by participating delegations:  


United States 



Speakers info 

Jason Furman [Bio]
Professor of the Practice of Economic Policy, Harvard Kennedy School
presenting Note on Market Concentration

Jonathan Baker [Bio]
Research Professor of Law, American University, Washington College of Law
presenting Market Power in the US Economy Today Link to an external site icon

Joshua Wright [Bio]
Professor, George Mason University and Executive Director of the Global Antitrust Institute
presenting Towards a Better Understanding of Concentration: Measuring Merger Policy Effectiveness

Hiro Odagiri [Bio]
Professor, Department of Economics, Hitotsubashi University
presenting Market Concentration and Competition Policy

Chiara Criscuolo [Bio]
Head of the OECD Productivity and Business Dynamics Division,
Directorate of Science, Technology and Innovation

About the discussion

Market concentration and market power in the US

Difficulties in measuring concentration and market power

Market concentration in Japan

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Chris Pike – OECD Competition Division 

Chiara Criscuolo – OECD Productivity & Business Dynamics Division 

Joshua Wright – George Mason University 



Jason Furman – Harvard 

Hiroyuki Odagiri – Hitotsubashi University 




Common ownership by institutional investors and its impact on competition (2017)

Evaluation of competition interventions


OECD Handbook on Competition Policy in the Digital Age

Abuse of dominance and monopolisation

Cartels and anti-competitive agreements

Competition enforcement practices

Liberalisation and competition intervention in regulated sectors


Pro-competitive Policy Reforms

Access the full list of Competition Policy Roundtables


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