Market Models and Heteroscedasticity of Residual Security Returns

Abstract

Bickel's tests provide attractive robust alternatives to traditional tests of heteroscedasticity. NYSE securities have homoscedastic residuals once nonnormality of security returns is allowed. Some portfolio designs may generate some heteroscedastic residuals, but this heteroscedasticity is reduced by the Kraus-Litzenberger quadratic market model. This result suggests a misspecification in the traditional market model.