An increasing body of empirical evidence is documenting trends toward rising concentration, profits, and markups in many industries around the world since the 1980s. Two major criticisms of these studies is that concentration and market shares are poorly measured at the national industry level...

This article seeks an answer to a question that should be well settled: for purposes of antitrust analysis, what is 'market power' and/or 'monopoly power'? The question should be well settled because antitrust law requires proof of actual or likely market power or monopoly power to establish...

The concept of market power is at the core of antitrust. Philosophically, antitrust policy is aimed primarily at preventing firms from achieving, retaining, or abusing market power. Operationally, assessing whether a firm or firms have market power or any reasonable prospect for achieving it is...

Economists have long recognized the National Collegiate Athletic Association (NCAA) as a monopsonistic cartel that restrains athlete labor compensation below competitive market levels. However, an additional restraint has been heretofore ignored. This article argues that NCAA justifies the...

The principal explanations in the existing economics literature for the formation of concentrated markets are intellectual property-related entry barriers, economies of scale, and network effects. In each of these explanations, a few firms have an inherent advantage, allowing them to maintain...

The prohibition of certain types of anticompetitive unilateral conduct by firms possessing a substantial degree of market power is a cornerstone of competition law regimes worldwide. Yet notwithstanding the social costs of monopoly modern legal regimes refrain from prohibiting it outright....

This handbook chapter appears in Antitrust Law & Economics (Keith Hylton, ed. 2010). It describes the role of market concentration in the legal framework for the antitrust review of horizontal mergers and evaluates the extent to which modern economic analysis supports a role for concentration in...

Recent theoretical research on the implications of two-sided markets is gaining recognition for its implications in antitrust. However, the role of empirical analysis in antitrust cases for two-sided markets has been unexplored thus far. Empirical tools of economics are playing an increasingly...