The European Union antitrust chief, Commissioner Margrethe Vestager, recently announced a major EU-wide inquiry on market restrictions on e-commerce . This horizontal market investigation is part of a top priority of the European Commission (i.e. the European Digital Single Market). This investigation is likely to significantly change the regulatory framework for retail commerce in Europe. It affects brands, manufacturers, distributors, internet market places and both offline and online retailers. The EU antitrust department will first investigate the market situation, seeking to understand the retail market dynamics from the perspective of removing restrictions on internet commerce and intra EU cross border trade. Typically, the EU authority will send questionnaires to the companies and collect an ample sample of contracts. In the process, the authority can open individual antitrust infringement procedures. The probe may also result in further policy guidance, inter alia concerning the balance between offline and online retail and the respective legal rights of the supply chain stakeholders. This Brussels initiative will be coordinating with ongoing enforcement and market studies at the European National States level. Additional implications in the digital chapter of the Transatlantic Trade and Investment Partnership negotiations are also possible.