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

Stephen Davies, Matthew Olczak, Heather Coles

Research output: Contribution to journalArticlepeer-review


This paper estimates the implicit model, especially the roles of size asymmetries and firm numbers, used by the European Commission to identify mergers with coordinated effects. This subset of cases offers an opportunity to shed empirical light on the conditions where a Competition Authority believes tacit collusion is most likely to arise. We find that, for the Commission, tacit collusion is a rare phenomenon, largely confined to markets of two, more or less symmetric, players. This is consistent with recent experimental literature, but contrasts with the facts on ‘hard-core’ collusion in which firm numbers and asymmetries are often much larger.
Original languageEnglish
Pages (from-to)221-231
Number of pages11
JournalInternational Journal of Industrial Organization
Issue number2
Publication statusPublished - Mar 2011


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


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