Evolving market boundaries and competition policy enforcement in the pharmaceutical industry Articles uri icon

publication date

  • April 2023

start page

  • 313

end page

  • 348


  • 2


  • 55

International Standard Serial Number (ISSN)

  • 0929-1261

Electronic International Standard Serial Number (EISSN)

  • 1572-9990


  • Competition investigations start with market definition, which establishes the perimeter of the competitive analysis. In this paper, we focus on the definition of economic markets in the pharmaceutical industry, where the entry of generics in different therapeutic areas provides a sequence of quasi-natural experiments involving a significant competitive shock for the originator producer. We show how generic entry modifies price and non-price competitive constraints over time, generating market-wide effects. Paradoxically, generic entry may soften the competitive pressure for brands other than the originator. We obtain these results by econometrically estimating time-varying price elasticities. We then apply the logic of the Hypothetical Monopolist Test to gauge the strength of competitive constraints under different market structures. Our results provide strong empirical support for an approach that defines relevant markets contingent on the theory of harm. We discuss the relevance of these findings in the context of ongoing cases.


  • Economics


  • antitrust; competition policy; market definition; pharmaceutical industry