25 years of European merger control

We study the evolution of the EC's merger decision procedure over the first 25 years of European competition policy. Using a novel dataset constructed at the level of the relevant markets and containing all merger cases over the 1990-2014 period, we evaluate how consistently arguments related to structural market parameters were applied over time. Using non-parametric machine learning techniques, we find that the importance of market shares and concentration measures has declined while the importance of barriers to entry and the risk of foreclosure has increased in the EC's merger assessment following the 2004 merger policy reform.