We derive a separation theorem: investors hold a common risk-adjusted market portfolio regardless of their information sets, and a portfolio based upon their private signals. This implies that investors have non-negligible holdings of assets they know little about, so nonparticipation remains a...

In a setting with information asymmetry and a tradable value-weighted market index, ambiguity averse investors hold undiversified portfolios, and assets have non-zero alphas. But when a passive fund offers the risk-adjusted market portfolio (RAMP) whose weights depend on information precisions...

Ambiguity aversion alone does not explain the market nonparticipation puzzle. We show that in a rational expectations equilibrium model with a fund offering the risk-adjusted market portfolio (RAMP), ambiguity averse investors hold the fund and an information-based portfolio, and thus...

Ambiguity aversion alone does not explain the market nonparticipation puzzle. We show that in a rational expectations equilibrium model with a fund offering the risk-adjusted market portfolio (RAMP), ambiguity averse investors hold the fund and an information-based portfolio, and thus...

Cost-of-capital assessments with factor models require quantitative forward- looking estimates. We recommend estimating Vasicek-shrunk betas with one to four years of daily stock returns, and then — because the underlying betas are themselves time-varying — shrinking betas a second time (and...

Presentation Slides for "Overconfidence, Arbitrage, and Equilibrium Asset Pricing" This paper offers a model in which asset prices reflect both covariance risk and misperceptions of firmsapos prospects, and in which arbitrageurs trade against mispricing. In equilibrium, expected returns are...

The basic paradigm of asset pricing is in vibrant flux. The purely rational approach is being subsumed by a broader approach based upon the psychology of investors. In this approach, security expected returns are determined by both risk and misvaluation. This survey sketches a framework for...

We propose a theoretically-motivated factor model based on investor psychology and assess its ability to explain the cross-section of U.S. equity returns. Our factor model augments the market factor with two factors which capture long- and short-horizon mispricing. The long-horizon factor...