Blockholders: A Survey of Theory and Evidence

This paper reviews the theoretical and empirical literature on the role of blockholders (large shareholders) in corporate governance. We start with the underlying property rights of public corporations; we discuss how blockholders are critical in addressing free-rider problems and why, like owners of private property in general, blockholders are likely to be active in firm governance. We then examine what distinguishes a blockholder from an ordinary shareholder and advocate additional definitions from the typical threshold of 5% ownership. We next present new evidence on the frequency and characteristics of blockholders in United States corporations. Then we develop a simple unifying model to present theories of blockholder governance through both voice (direct intervention) and exit (selling one's shares). We survey the empirical evidence on blockholder governance, emphasizing the empirical challenges in identifying causal effects involving blockholders. We highlight the lack of credible instruments for blockholders and argue that exogenous variation should not be a prerequisite for research---a narrow focus on identification may lead to a focus on identifying narrow questions. We emphasize the value of descriptive research with blockholders and how endogeneity concerns can be addressed with economic logic and by directly testing alternative explanations. We close with suggestions for future research.