A theoretical approach to market definition analysis

This work performs a theoretical approach to market definition analysis. The conditions a test must satisfy are selected in order to define the relevant market according to the jurisdictions of the United States and the European Union as most tests proposed by economists tend not to satisfy all the required conditions. I use two models of horizontal product differentiation to illustrate the nature of the tests that can be used under each jurisdiction. The main conclusion of the paper is that the empirical tests for market definition which are valid in the current legislations in the United States and the European Union must be performed using a different approach which may yield different relevant markets.