This article analyzes the manifold situations in which the efficient-market hypothesis (EMH) has influenced — or has failed to influence — federal securities regulation and state corporate law, and the prospective roles for the EMH in these contexts. In federal securities regulation, the EMH...

I examine whether the Securities and Exchange Commission (SEC) in the US is a learning organization (i.e., one that is capable of learning and adaptation to the dynamic nature of the securities markets – the subject of the SEC's regulatory oversight). Using the treatment of public corporate...

The problem of managerial agency costs dominates debates in corporate law. Many leading scholars advocate reforms that would reduce agency costs by forcing firms to allocate more control to shareholders. Such proposals disregard the costs that shareholders avoid by delegating control to managers...

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...

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...

A phenomenon known as “Common Ownership” arises when shareholders hold substantial stakes in competing firms. Although recent empirical evidence has illustrated how common concentrated owners are associated with higher product market prices and lower output, scholars remain divided as to the...

Common ownership exists when investors concurrently hold partial and significant shares in related firms. In this paper, I compile, document, and taxonomize 30 separate cases of intervention to demonstrate how common owners influence firm behavior. Although previous literature has identified a...

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...