Hub-and-Spoke Collusion: What’s the Role of the Fifth Wheel?

Hub-and-spoke cartels are horizontal in nature, but they involve a “hub” (that can be a common supplier, customer, platform, or intermediary) who intermediates and often cements the agreement between the spokes. While the role of the hub appears to be crucial, its incentives are not always clear. Why would the hub want to increase the margins of its customers or suppliers? This review synthesizes a recent literature that analyzes the role and incentives of the hub. As hub-and-spoke theories