We show theoretically that the responsiveness of a fund manager’s portfolio allocations to changes in public information decreases in the manager’s skill. We go on to estimate this sensitivity (RPI) as the R² of the regression of changes in a manager’s portfolio holdings on changes in public information using a panel of U.S. equity funds. Consistent with RPI containing information related to managerial skills, we find a strong inverse relationship between RPI and various existing measures of performance, and between RPI and fund flows. We also document that both fund- and manager-specific attributes affect RPI.