Multiple blockholder structures are a widespread phenomenon in the U.S. The theoretical literature, however, provides conflicting predictions on whether a single large blockholder or a set of dispersed smaller blockholders is better for firm value. Using U.S. data, we find a negative correlation between Tobin's Q and blockholder dispersion. The findings are robust to a wide variety of model specifications and controls and differ from results for other geographic regions such as Europe and Asia. © 2011 Elsevier B.V.