Market definition and market power are central features of competition law and practice but pose serious challenges. On one hand, market definition suffers decisive logical infirmities that render it infeasible, unnecessary, and counterproductive, and the practice of stating market power...

This survey examines recent developments in economic research relating to antitrust, paying specific attention to research in the areas of collusion and merger enforcement. Research relating to both collusion and mergers has made significant advances in the last twenty years. With respect to...

Antitrust authorities search public documents to discover anticompetitive mergers. Thus, investor disclosures may alert them to deals that would otherwise escape scrutiny, creating disincentives for managers to divulge transactions. We study this behavior in publicly traded US companies. First,...

This paper considers the recent literature on firm markups in light of both new and classic work in the field of Industrial Organization. We detail the shortcomings of papers that rely on discredited approaches from the "structure-conduct-performance" literature. In contrast, papers based on...

While economic theories indicate that market power by downstream firms can potentially counteract market power upstream, antitrust policy is opaque about whether to incorporate countervailing market power in merger analyses. We use detailed national claims data from the healthcare sector to...

We examine the capital-market effects of changes in securities regulation in the European Union (EU) aimed at reducing market abuse and increasing transparency. To estimate causal effects for the population of EU firms, we exploit that for plausibly exogenous reasons, like national legislative...

A diversion ratio, which measures the fraction of consumers that switch from one product to an alternative after a price increase, is a central calculation of interest to antitrust authorities for analyzing horizontal mergers. Two ways to measure diversion are: the ratio of estimated cross-price...

We propose a method for bounding the demand elasticity in growing, homogeneous-product markets that requires only minimal data--market price and quantity over a time span as short as two periods. Reminiscent of revealed-preference arguments using choices over time to bound the shape of...

Many standard setting organizations (SSOs) require participants to disclose patents that might be infringed by implementing a proposed standard, and commit to license their "essential" patents on terms that are at least fair, reasonable and non-discriminatory (FRAND). Data from these SSO...

This article addresses developments in the literature on The Rise of Market Power. First, it summarizes research about the result of De Loecker 2020 that the sales-weighted average markup has increased in the United States. Second, it summarizes and evaluates a set of industry studies that...