Professor Louis Kaplow capped off his series on the relevant market with a final essay in this the Antitrust Law Journal. His premise remains that relevant market is used only to help assess a firm's market power based on its market share. He claims: (1) “there exists no valid way to make...

A merger retrospectives research agenda should be pursued. It should stress careful evaluation of agency assessments of the competitive effects of mergers in the hope of improving the accuracy of the enforcement process. But several inconvenient truths may prevent much from being learned, and...

The rule of reason is the standard for testing whether a restraint of trade violates the Sherman Act. The thesis of this article is that the only issue under the rule of reason is the impact of a restraint on the competitive process; the Sherman Act does not employ a welfare standard. This...

We propose a simple method for predicting price effects from mergers between branded retail chains competing in many local markets. When past mergers created markets with the same number of brands but different numbers of brand owners, price data at a single point in time exhibit between-market...

Inconvenient truths prevent econometric merger retrospective studies from substantially altering our understanding of competitive effects from horizontal mergers. Econometrics cannot definitively determine the effects of particular mergers, and if they could, econometric merger retrospectives...

In FTC v. Lundbeck, courts rejected a challenge to an acquisition placing under common control the only two drugs for treating a heart defect in newborns. Although the court decisions in the case have been severely criticized, they might well have achieved the right result for the right reason....

The digital economy presents challenges for antitrust law, but changes in substantive antitrust law are not needed to cope with them. The biggest problem in antitrust today is that the courts impose excessive burdens on plaintiffs, but no constructive solution to that problem is evident, and...

European enforcers have brought high-profile antitrust cases against the tech giants, and both activists and members of Congress are calling for action in the United States. This short note identifies ten hard-wired differences between the European and American enforcement regimes that make very...

Horizontal mergers give rise to unilateral anticompetitive effects if they cause the merged firm to act less intensely competitive than the merging firms, while non-merging rivals do not alter their competitive strategies. This chapter describes the economic theory underlying unilateral...