CAPM verification using overnight and daytime returns

Abstract

Purpose – The capital asset pricing model has failed to explain the effect of systematic risk (referred to as beta) on actual stock market returns. Accordingly, this study analyzes daily returns by splitting it into overnight and daytime returns. The study analysis empirically confirms a positive relationship between overnight returns and beta and a negative relation between daytime returns and beta. Furthermore, this paper aims to determine that empirical results are mostly the same with three different beta calculations, namely, daily, overnight and daytime returns. The study concludes that beta on overnight returns has the strongest explanatory power and is statistically significant.