Beyond horizontal harm: Digital ecosystems, innovation, and the future of European merger control

This paper develops four proposals to modernize merger control in the European Union and beyond. First, merger control should be reinforced and reinvigorated to prevent the further rising of market power and to stop the ongoing decline of competition intensity. Second, the analysis highlights the need to incorporate systemic and cross-market power into both market definition and competitive assessment. Third, it challenges the traditional presumption that non-horizontal mergers are generally less harmful than horizontal ones, showing that vertical and conglomerate integration may reinforce ecosystem power and foreclose innovation. Finally, the paper proposes the use of rebuttable presumptions to address procedural asymmetries and under-enforcement. Together, these reforms would align merger control with contemporary economic research on digital ecosystems and enhance its capacity to safeguard contestability, innovation, and dynamic competition.