Relation between Time-Series and Cross-Sectional Effects of Idiosyncratic Variance on Stock Returns

Abstract

Consistent with the post-1962 U.S. evidence by Ang, Hodrick, Xing, and Zhang [Ang, A., Hodrick, R., Xing Y., Zhang, X., 2006. The cross-section of volatility and expected returns. Journal of Finance 51, 259-299.], we find that stocks with high idiosyncratic variance (IV) have low CAPM-adjusted expected returns in both pre-1962 U.S. and modern G7 data. We also test in three ways the conjecture that IV is a proxy of systematic risk. First, the return difference between low and high IV stocks -- that we dub as IVF -- is a priced factor in the cross-section of stock returns. Second, loadings on lagged market variance and lagged average IV account for a significant portion of variation in average returns on portfolios sorted by IV. Third, the variance of IVF correlates closely with average IV, and the two variables have similar explanatory power for the time-series and cross-sectional stock returns.

Keywords: Stock return predictability, Average idiosyncratic variance, Stock market variance, Cross-section of stock returns, Value premium, CAPM

JEL Classification: G1