Separation of powers arguments may play a role in antitrust. The opposite is also true, as antitrust may influence the separation of powers envisaged in a broad – political and economic – perspective. Indeed, the concentration of power by a few companies of the digital economy reveals data, platform and politico-economic powers, which may lead to a rethinking of our understanding of separation of powers and let us question the role of antitrust de lege lata in this regard. One of the difficult tasks posed by antitrust typically consists of defining the relevant markets, often a key element of antitrust analysis and enforcement. Once the markets are defined, data access, portability, sharing, and interoperability, as well as the interdiction of abusive discrimination, raise fundamental issues from a politico-economic perspective of or on the separation of powers principles and antitrust. Discrimination by a dominant firm may trigger the application of antitrust or competition laws. Ultimately, antitrust may contribute to deconcentrate data or platform power and support some form of separation of powers from a politico-economic perspective.