We investigate the portfolio choices of mean-variance-optimizing investors who use sample evidence to update prior beliefs centered on either risk-based or characteristic-based pricing models. With dogmatic beliefs in such models and an unconstrained ratio of position size to capital, optimal...

A plot of expected returns versus betas obeys virtually no relation to an inefficient index portfolio's mean-variance location. If the index portfolio is inefficient, then the coefficients and R- squared from an ordinary-least-squares regression of expected returns on betas can equal essentially...

Greater skill of active investment managers can mean less fee revenue in a general equilibrium. Although more-skilled managers earn more revenue than less-skilled managers, greater skill for active managers overall can imply less revenue for their industry. Greater skill allows managers to...

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...

Extremely long odds accompany the chance that spurious-regression bias accounts for investor sentiment's observed role in stock-return anomalies. We replace investor sentiment with a simulated persistent series in regressions reported by Stambaugh, Yu and Yuan (2012), who find higher long-short...

We estimate financial institutions' portfolio tilts that relate to stocks' environmental, social, and governance (ESG) characteristics. We find ESG-related tilts totaling 6% of the investment industry's assets under management in 2021. ESG tilts are significant at both the extensive margin...

We derive equilibrium relations among active mutual funds' key characteristics: fund size, expense ratio, turnover, and portfolio liquidity. As our model predicts, funds with smaller size, higher expense ratios, and lower turnover hold less liquid portfolios. A portfolio's liquidity, a concept...