The ex post efficient frontier is the tradeoff between portfolio average return and standard deviation which could have been attained in some capital market over a set of consecutive historical subperiods. This article formulates three different problems of deriving the ex post efficient frontier. These problems differ in the extent to which portfolio revision is permitted between subperiods. The ex post efficient frontier may be useful as a reference point in evaluating the performance of mutual funds and other institutional portfolios. This is illustrated for a set of Swedish mutual funds.
