We model how investors allocate between asset managers, managers choose their portfolios of multiple securities, fees are set, and security prices are determined. The optimal passive portfolio is linked to the “expected market portfolio,” while the optimal active portfolio has elements of...

"We present a model in which some investors are prohibited from using leverage and other investors' leverage is limited by margin requirements. The former investors bid up high-beta assets while the latter agents trade to profit from this, but must de-lever when they hit their margin...

We argue that active management's popularity is not puzzling despite the industry's poor track record. Our explanation features decreasing returns to scale: As the industry's size increases, every manager's ability to outperform passive benchmarks declines. The poor track record occurred before...

We analyze the equilibrium size of the active management industry and the role of historical data - how investors use it to decide how much to invest in the industry, and how researchers use it to judge whether the industry's size is reasonable. As the industry's size increases, every manager's...

We present a model in which some investors are prohibited from using leverage and other investors' leverage is limited by margin requirements. The former investors bid up high-beta assets while the latter agents trade to profit from this, but must de-lever when they hit their margin constraints....