Merger to Monopsony: An Efficiencies Defense

Abstract

In a classic article, Oliver Williamson introduced the efficiency defense to antitrust merger analysis. In this article, I extend his analysis to mergers among buyers that may create monopsony power. When such mergers are accompanied by merger-specific efficiencies, there is necessarily a welfare tradeoff. Evaluating the impact of the merger on social welfare requires a comparison of the cost savings that can be realized only without the merger and the allocative inefficiency due to the exercise of monopsony power.