Based on Markowitz's pioneering study [40], Sharpe [56] and Lintner [38] advanced the first positivist formulations of the capital asset pricing model (CAPM). Their models were subsequently refined by Mossin [45], Fama [15], Black [1], and others. Even though the CAPM has been studied extensively, it has not been empirically validated. According to Roll [48], the CAPM cannot be tested in an unambiguous fashion because of a number of intractable measurement and computational difficulties, and the joint nature of the hypotheses to be tested.