Tacit collusion, firm asymmetries and numbers: evidence from EC merger cases

Stephen Davies, Matthew Olczak, Heather Coles

Research output: Preprint or Working paperWorking paper


The purpose of this paper is to identify empirically the implicit structural model, especially the roles of size asymmetries and concentration, used by the European Commission to identify mergers with coordinated effects (i.e. collective dominance). Apart from its obvious policy-relevance, the paper is designed to shed empirical light on the conditions under which tacit collusion is most likely. We construct a database relating to 62 candidate mergers and find that, in the eyes of the Commission, tacit collusion in this context virtually never involves more than two firms and requires close symmetry in the market shares of the two firms.
Original languageEnglish
Place of PublicationNorwich (UK)
PublisherUniversity of East Anglia
Number of pages38
Publication statusPublished - Apr 2007

Publication series

NameCCP working paper
PublisherCentre for Competition Policy
ISSN (Print)1745-9648


  • tacit collusion
  • collective dominance
  • coordinated effects
  • European mergers
  • asymmetries


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