La definición del mercado relevante en la economía de plataformas: a propósito del caso Facebook Marketplace

The definition of the relevant market is an essential step in the application of competition law, as it provides the basis for assessing firms’ market power. However, this task is particularly complex in the context of digital platforms, which are characterized by their multilateral nature, the presence of network effects, the provision of free services, and the importance of data. These specific features challenge the adequacy of traditional market definition techniques and have led competition authorities to adapt their analytical tools. In this context, the present paper examines the European Commission’s Decision in the Facebook Marketplace case (2024), a key development in the application of Article 102 TFEU to online platforms. This decision makes significant contributions in the areas of market definition and market power assessment, adjusting classical criteria to the dynamics of digital environments. After a brief summary of the facts and the Commission’s conclusions, the paper analyses in detail the relevant markets defined and the methodology employed, assessing their consistency with the 2024 Market Definition Notice and previous decisional practice. It also highlights the new guidance that this Decision provides for the exercise of market definition and the calculation of market shares in the context of digital platforms.