Market Shares as Collusive Marker: Evidence from the European Truck Industry

Collusion theory robustly predicts non-cartel rivals to raise their price and increase their output. As the typical cartel cuts back production, its competitors are expected to gain market share during the collusive period and to lose market share in
the period following the cartel's demise. We provide empirical support for this prediction by showing that it applied to the European truck cartel. We also illustrate how our analysis can be used in the prosecution stage. One truck manufacturer
denied cartel participation, whereas the proposed market share test supports the European Commission's finding that this firm was, in fact, a member.