Market Definition in Antitrust Analysis: A Regression-Based Approach

Abstract

Alleged violations of either Sherman ?2's antimonopoly strictures or Clayton ?7's proscriptions against anticompetitive mergers, necessarily involve a particular product, and must occur in a particular place. That is, the plaintiff in either a ?2 or ?7 suit must define a relevant market within which the violation alleged has occurred.' Even in the most mundane antitrust analysis, however, market definition is rarely readily accomplished and unaccompanied by a series of caveats, and the possibility of the opposing parties in an antitrust suit failing to contest each other's proffered definition is virtually nil.2 Because economists, from