Tests of the CAPM with Time‐Varying Covariances: A Multivariate GARCH Approach
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- Author(s): LILIAN NG
- Published: Apr 30, 2012
- Pages: 1507-1521
- DOI: 10.1111/j.1540-6261.1991.tb04628.x
This paper examines an asset pricing model in which the Sharpe‐Lintner CAPM and the zero‐beta CAPM are special cases. The model allows the ratio of expected market risk premium to market variance, the conditional expected excess returns, and the risks to change over time. The results are found to be sensitive to the choice of the portfolio formation techniques. Significant time variability is shown in the conditional expected excess asset returns and risks and also in the reward‐to‐risk ratio.