The objective of the study was to assist the Commission’s Impact Assessment process in providing it with robust evidence as regards issues linked with gatekeeping power of digital platforms with strong data-driven network effects, and a structured analysis of problems raised by those platforms. To this end, the study also aimed at providing technical, legal, and economic analysis of the dynamics of digital platform ecosystems, which occur outside the existing competition law-notion of relevant markets. It also supported the Impact Assessment by scoping the parameters of intervention (economic players in scope of the initiative and criteria relevant to identify these players) and helping to identify possible policy options and providing preliminary analysis of their impact. The insights provided by the study aimed to support the Commission’s Impact Assessment and underpin its policy measures.