Asymmetric Collusion with Growing Demand

We characterize collusion sustainability in markets where demand growth triggers the entry of a new firm whose efficiency may be different from the efficiency of the incumbents. We find that the profit-sharing rule that firms adopt to divide the cartel profit after entry is a key determinant of the incentives for collusion (before and after entry). In particular, if the incumbents and the entrant are very asymmetric, collusion without side-payments cannot be sustained. However, if firms divide joint profits through bargaining and are sufficiently patient, collusion is sustainable even if firms are very asymmetric.