Cartels are inherently instable. Each cartelist is best off if it breaks the cartel, while the remain-ing firms remain loyal. If firms interact only once, if products are homogenous, if firms compete in price, and if marginal cost is constant, theory even predicts that strategic interaction...

A cartel is socially not desirable. But is it a normative problem? And has merger control reason to be concerned about tacit collusion? Neither is evident once one has seen that the members of a cartel face a problem of strategic interaction. It is routinely analysed in terms of game theory....