The requirement of positive marginal utility only makes it possible to derive a restricted twofund separation theorem for portfolio selection problems replacing the original separation theorem of Cass and Stiglitz (1970). We use our findings for a re-examination of the bias-in-beta problem in...

Our main goal is the generalization of the approach of Jobson and Korkie(1984) for funds performance evaluation. Therefore, we consider the portfolio selection problem of an investor who faces short sales restrictions when choosing among F different investment funds and assume the investor's...