The International Antitrust Paradox

Abstract

Large multinational mergers are routinely reviewed by multiple antitrust authorities across jurisdictions. While each authority applies domestic law, approval of a global transaction effectively requires clearance from all major regulators. This paper shows that such a system generates a "most restrictive regulator" equilibrium, in which the jurisdiction imposing the strictest remedy or prohibition determines global outcomes. We present a simple model of multi-jurisdictional merger review that yields testable predictions on approval probabilities, remedy incidence, and review duration as a function of the number and composition of reviewing authorities. Using a novel dataset of large cross-border mergers, we provide evidence that merger outcomes are disproportionately shaped by a small set of pivotal jurisdictions. The results highlight how decentralized antitrust enforcement creates de facto global regulation without centralized governance.