Has the antitrust arsenal run out of novel theories or weapons? Think again. Recent scholarship has come to challenge conventional wisdom with the latest target of antitrust imagination being institutional investors, including diversified index funds. New economic research suggests that common...

Some scholars have argued that common ownership, which refers to an investor's simultaneous ownership of small stockholdings in several competing companies, is anticompetitive and prohibited by the U.S. antitrust laws. Proponents of this view target in particular large investment managers that...

Partial ownership of stock in multiple competing firms is an important scholarly and policy topic in both corporate and antitrust law. Until now, the discussion has focused on ownership. This essay shifts the debate from a focus on common ownership to a focus on common control. No prior work has...

Minority shareholdings have been on the regulatory agenda of competition authorities for some time. Recent empirical studies, however, draw attention to a new, thought provoking theory of harm: common ownership by institutional investors holding small, parallel equity positions in several...

Empirical evidence that horizontal shareholding has created anticompetitive effects in airline and banking markets have produced calls for antitrust enforcement. In response, others have critiqued the airline and banking studies and argued that antitrust law cannot tackle any anticompetitive...

Horizontal shareholding exists when significant shareholders have stock in horizontal competitors. (It is often imprecisely called "common shareholding," but that term can also apply when shareholders own stock in two noncompeting corporations. It differs from "cross-shareholding," which...

This Article shows that 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,...

Horizontal shareholdings exist when a common set of investors own significant shares in corporations that are horizontal competitors in a product market. Economic models show that substantial horizontal shareholdings are likely to anticompetitively raise prices when the owned businesses compete...

Although empirical studies show that common shareholding affects corporate conduct and that common horizontal shareholding lessens competition, critics have argued that the law should not take any action until we have clearer proof on the causal mechanisms. I show that we actually have ample...

Scholars and antitrust enforcers have raised concerns about anticompetitive effects that may arise when institutional investors hold substantial stakes in competing firms. Their concern rests on empirical evidence that such common concentrated ownership is associated with higher prices and lower...