Monopolization through endogenous vertical mergers

While endogenous merger analysis has been applied to horizontal mergers, the thrust of vertical merger analysis has been based on exogenous mergers. The goal of this paper is to analyze endogenous vertical mergers. I consider a market structure with a downstream monopolist and an oligopolistic upstream industry. The downstream monopolist chooses to buy a certain number of the upstream firms. Mergers are endogenous, in the sense that the bids made by the downstream firm must be accepted by each of the integrated upstream firms, and must not exceed the increase in the profits of the downstream firm. It is shown that the unique equilibrium is complete monopolization: the buyer buys all the firms in the upstream industry. This result is consistent with the result that vertical mergers are profitable. However, it is in contrast with horizontal endogenous mergers, where complete monopolization is generally not an equilibrium.