Economic analysis of competition regulation is most developed in the domain of horizontal mergers, and modern agency guidelines reflect a substantial consensus on the appropriate template for merger assessment. Nevertheless, official protocols are understood to rest on a problematic market...

This is a survey of the economic principles that underlie antitrust law and how those principles relate to competition policy. We address four core subject areas: market power, collusion, mergers between competitors, and monopolization. In each area, we select the most relevant portions of...

The recently issued revision of the U.S. Horizontal Merger Guidelines, like its predecessors and mirrored by similar guidelines throughout the world, devotes substantial attention to the market definition process and the implications of market shares in the market that is selected. Nevertheless,...

Market definition has long held a central place in competition law. This entry surveys recent analytical work that has called the market definition paradigm into question on a number of fronts: whether the process is feasible, whether market share threshold tests are coherent, whether the...