The supposed ubiquity of potential efficiencies is understood to justify permitting most horizontal mergers despite their tendency to raise prices. Yet efficiencies are said to be rarely decisive in actual merger decision-making. Moreover, the economic analysis of merger efficiencies lags far...

This article explores the many ways that entry is relevant to horizontal merger analysis.Only one, however, is part of the current canon, and it is handled incorrectly. The analysisdraws on work in industrial organization economics that examines entry in imperfectlycompetitive markets. Ex post...

Despite decades of research on mechanism design and on many practical aspects of cost-benefit analysis, one of the most basic and ubiquitous features of regulation as actually implemented throughout the world has received little theoretical attention: exemptions for small firms. These firms may...

This article examines optimal policy toward coordinated oligopolistic price elevation. First, it analyzes the social welfare implications of enforcement, elaborating the value of deterrence and the nature of possible chilling effects. Then, it explores a variety of means of detection, with...