We show theoretically and empirically that flows into index funds raise the prices of large stocks in the index disproportionately more than the prices of small stocks. Conversely, flows predict a high future return of the small-minus-large index portfolio. This finding runs counter to the CAPM,...

We derive equilibrium asset prices when fund managers deviate from benchmark indices to exploit noise-trader induced distortions but fund investors constrain these deviations. Because constraints force managers to buy assets that they underweight when these assets appreciate, overvalued assets...

We propose a rational theory of momentum and reversal based on delegated portfolio management. An investor can hold assets through an index or an active fund. Investing in the active fund involves a time-varying cost, interpreted as managerial perk or ability. The investor responds to an...

We study flows between investment funds and their effects on asset prices in a simple two-period version of Vayanos and Woolley (2010, VW). As in VW, flows cause assets to comove in ways unrelated to fundamentals, affect assets with high idiosyncratic risk the most, and raise the expected...