Comparing Merger Policies in the European Union and the United States

We collect a sample of EU and US merger investigations, estimate models of the regulatory decisions, and use the models to compare merger policies. Our approach allows us to decompose observed differences into policy effects and case-mix effects. Focusing on dominance mergers, we find that the EU is tougher than the US on average, in particular for mergers resulting in moderate market shares. However, the US appears to be more aggressive for coordinated interaction and non-dominance unilateral effects cases. Overall, our analysis detects substantial differences in policies, but it does not classify one regime as being more aggressive than the other.