General Equilibrium in Vertical Market Structures: Overselling versus Overbuying

The lens used by the courts and much of the antitrust literature on predatory selling and/or buying is based on partial equilibrium methodology. We demonstrate that such methodology is unreliable for assessments of predatory monopoly or monopsony conduct. In contrast to the typical two-stage dynamic analysis involving a predation period followed by a recoupment period, we advance a general equilibrium analysis that demonstrates the critical role of related industries and markets. Substitutability versus complementarity of both inputs and outputs is critical. With either monopolistic or monopsonistic market power (but not both), neither predatory overselling nor predatory overbuying is profitably sustainable. Two-stage predation/recoupment is profitable only with irreversibility in production and cost functions, unlike typical estimated forms from the production economic literature. However, when the market structure admits both monopolistic and monopsonistic behavior, predatory overbuying can be profitably sustainable while overselling cannot. Useful distinctions are drawn between contract versus non-contract markets for input markets.