The dynamics of market boundaries and the role of systemic market power

Abstract Identifying the boundaries of a market is a critical component of most antitrust and competition policy areas. While there are established practices for market definition and delineation, dynamic processes of competition and the novel phenomenon of (digital) ecosystems provide new challenges: market boundaries become (i) inherently dynamic and subject to evolutionary change and (ii) subject to the deliberate design of powerful companies. Consequently, the prediction of post-event effects—for example, competitive effects resulting from a merger or an instance of abuse of market power—may fail if it relies on a static or stationary market definition. If market boundaries change inherently through dynamic market competition, identifying these boundaries and their evolution becomes an integral part of a dynamic approach to competition policy rather than mere preparatory work. Furthermore, if companies wield systemic market power within ecosystems (eg cross-market power) and thus have the power to shape market boundaries and deliberately alter (previous) market delineations, the identification of market boundaries cannot be regarded independently of the exploitation of market power. Both dynamics of market boundaries necessitate a different approach to market definition than the one outlined in the Commission’s 2024 Market Definition Notice.