The critical loss test proposed by Barry Harris and Joseph Simons has become popular in helping define U.S. antitrust markets. The test commonly leads to large, inclusive markets. We show that it is problematic, for several reasons.

This paper examines a moral hazard problem faced by the owners of fleet automobiles. because fleet vehicules are generally not driven by their owners, the drivers of these vehicules do not bear all of the costs of either neglecting or abusing the vehicule.

Antiturst enforcement agencies and courts use net effect on price as a touchstone for the legality of mergers. This paper derives a simple, and completely general, condition for implementing that standard when industry equilibrium is static Nash in qualities (Cournot).