Ambiguity and the Skewness Premium

Abstract

Assets are priced according to the preferences of investors. Our theoretical model shows that ambiguity - that is the uncertainty about stock returns’ probability distribution - affects investors' preferences for the skewness of stock returns. In a CAPM equilibrium, skewness premiums increase when stock returns become more ambiguous. We test this interaction empirically and find evidence for it both cross-sectionally and when considering within-firm variation. Our findings hold for both skewness in historical stock returns and expected risk-neutral skewness calculated from option prices. They cannot be explained by limits to arbitrage, news tangibility, or investor belief heterogeneity. 

Keywords: Ambiguity, Probability Weighting, Skewness, Asset Pricing

JEL Classification: D53, D81, G11, G12