This study revisits the risk-return relationships in the Hong Kong stock market using a conditional model based on up and down markets. Beta is found significantly and positively (negatively) related to realized returns when the market excess returns are positive (negative). The same results are...

The intertemporal stability of the covariance matrix of stock returns is important in using ex-post factor structures on the APT and in portfolio optimization, while that of the correlation matrix is important in examining the ex-ante diversification benefits and stock return co-movements. By...