A theory of hub-and-spoke collusion

We develop a model of hub-and-spoke collusion between a manufacturer and two retailers. Demand is stochastic, and collusion between retailers is difficult; the best collusive equilibrium is inefficient (Rotemberg and Saloner (1986)). In the hub-and-spoke collusive agreement, retailers transmit their information about the state of demand to the supplier. The supplier uses this information to adjust the wholesale price. By organizing the collusion, the supplier increases profits of the vertical chain. We show that, surprisingly, this type of collusive agreement can under some conditions improve consumer welfare.