Abstract: This Article focuses on the power and corporate governance significance of the three largest index fund managers commonly referred to collectively as the "Big Three." We present current evidence on the substantial voting power of the Big Three and explain why it is likely to persist and, indeed, further grow. We show that, due to their voting power, the Big Three have considerable influence on corporate outcomes through both what they do and what they fail to do. We also discuss the Big Three's undesirable incentives both to underinvest in stewardship and to be excessively deferential to corporate managers. In the course of our analysis, we reply to responses and challenges to our earlier work on these issues that have been put forward by high-level officers of the Big Three and by a significant number of prominent academics. We show that these attempts to downplay Big Three power or the problems with their incentives do not hold up to scrutiny. We conclude by discussing the substantial stakes in this debate--the critical importance of recognizing the power of the Big Three, and why it matters.