How Horizontal Shareholding Harms Our Economy – And Why Antitrust Law Can Fix It
By Einer Elhauge (Harvard Law School)
New economic proofs and empirical evidence provide powerful confirmation that, even when horizontal shareholders individually have minority stakes, horizontal shareholding in concentrated markets often has anticompetitive effects. The new economic proofs show that, without any need for coordination or communication, horizontal shareholding will cause corporate managers to lessen competition to the extent they care about their vote share or re-election odds and will cause executive compensation to be less sensitive to firm performance. The new empirical evidence includes two new cross-industry studies which confirm that, just as the proofs predict, increased horizontal shareholding reduces the sensitivity of executive compensation to firm performance and increases the gap between corporate profits and investment. The new empirical evidence also includes two new industry studies that extend to the pharmaceutical industry the two prior industry studies finding that horizontal shareholding had anticompetitive effects in airline and banking markets. I also provide new analysis demonstrating that critiques of the airline and banking industry studies either conflict with the evidence or, when taken into account, increase the estimated adverse price effects from horizontal shareholding. I further provide new theoretical and factual explanations to show why, contrary to the claims of others, non-horizontal shareholder interests, vertical shareholdings, and index fund incentives do not prevent anticompetitive effects from horizontal shareholding. Finally, I provide new legal theories for tackling the problem of horizontal shareholding. I show that when horizontal shareholding has anticompetitive effects, it is illegal not only under Clayton Act §7, but also under Sherman Act §1. In fact, the historic trusts that were the core target of antitrust law were horizontal shareholders. I further show that anticompetitive horizontal shareholding also constitutes an illegal agreement or concerted practice under EU Treaty Article 101, as well as an abuse of collective dominance under Article 102. I conclude by showing that horizontal shareholding not only lessens the market concentration that traditional merger law can tolerate, but also means that what otherwise seem like non-horizontal mergers should often be treated as horizontal. Those implications for traditional merger analysis become even stronger if we fail to tackle horizontal shareholding directly.
Featured News
Federal Judge Lays Out Rules for States Challenging HPE–Juniper Deal
Jan 2, 2026 by
CPI
Federal Antitrust Suit Targeting Aircraft Engine Sales Practices Is Settled
Dec 31, 2025 by
CPI
CFTC Withdraws Guidance on ‘Actual Delivery’ in Crypto Transactions, Leaving Regulatory Void
Dec 31, 2025 by
CPI
Coalition of State AGs Push Back Against FCC Proposal Seeking to Preempt State AI Laws
Dec 31, 2025 by
CPI
Apple Seeks to Overturn £1.5 Billion UK App Store Antitrust Ruling
Dec 31, 2025 by
CPI
Antitrust Mix by CPI
Antitrust Chronicle® – CRESSE Insights
Dec 16, 2025 by
CPI
Learning from Divergence: The Role of Cross-Country Comparisons in the Evaluation of the DMA
Dec 16, 2025 by
Federico Bruni
New Regulatory Tools for the EU Foreign Direct Investment Screening and Foreign Subsidies Regulation
Dec 16, 2025 by
Ioannis Kokkoris
“Suite Dreams”: Market Definition and Complementarity in the Digital Age
Dec 16, 2025 by
Romain Bizet & Matteo Foschi
The Interaction Between Competition Policy and Consumer Protection: Institutional Design, Behavioral Insights, and Emerging Challenges in Digital Markets
Dec 16, 2025 by
Alessandra Tonazzi