The mean-semivariance CAPM strongly outperforms the traditional mean-variance CAPM in terms of its ability to explain the cross-section of US stock returns. If regular beta is replaced by downside beta, the traditional risk-return relationship is restored. The downside betas of low-beta stocks are substantially higher than the regular betas, while high-beta stocks involve less systematic downside risk than suggested by their regular betas. This pattern is especially pronounced during bad states-of-the-world, when the market risk premium is high. In sum, our results provide evidence in favor of market portfolio efficiency, provided we account for conditional downside risk.

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ERIM Report Series Research in Management
Erasmus Research Institute of Management

Post, G.T, & van Vliet, P. (2004). Conditional Downside Risk and the CAPM (No. ERS-2004-048-F&A). ERIM Report Series Research in Management. Retrieved from