Research Topics in Unilateral Effects Analysis

This chapter has been prepared for inclusion in the RESEARCH HANDBOOK ON THE ECONOMICS OF ANTITRUST LAW (Einer Elhauge, ed.). It first explains why unilateral effects may result from horizontal mergers, and then describes several key models that have been developed to gauge the likelihood and/or magnitude of unilateral effects, focusing on mergers in differentiated product Bertrand markets. The remaining sections discuss extensions to these models and measurement issues that arise when implementing unilateral effects analysis in practice, highlighting ongoing and potential future topics for research