Thresholds defined on the level and change in the HHI (Herfindahl-Hirschmann Index) applied to market shares seem to be the main instrument to select notified mergers for investigation in both the EU and US. We question the use of such a selection rule in differentiated products industries. We...

EU Merger Control Regulation No 4064/89 tended to rely on a dominance test, based on the market share of undertakings, to indicate the level and potential changes in market power. The use of such in differentiated product industries is questionable. New EC Merger Regulation No 139/2004...