My paper discusses four empirical approaches of the Russell 1000/2000 index reconstitutions to identify the effects of institutional investors on firm outcomes. Unbiased empirical approaches suggest that between 1998 and 2006, firms ranked at the top of the Russell 2000 had at most a 2% points higher ownership of passive investors than firms ranked at the bottom of the Russell 1000. There is no significant difference in total institutional ownership around the threshold. Thus, the quasi-experiment can only identify the effects of passive investors. I also find that passive investors have no significant effect on corporate social responsibility (CSR).