Abstract

The optimal portfolio strategy is developed for an investor who has detected an asset pricing anomaly but is not certain that the anomaly is genuine rather than merely apparent. The analysis takes account of the fact that the parameters of both the underlying asset pricing model and the anomalous returns are estimated rather than known. The value that an investor would place on the ability to invest to exploit the apparent anomaly is also derived and illustrative calculations are presented for the Fama-French SMB and HML portfolios, whose returns are anomalous relative to the CAPM. An asset pricing anomaly is a statistically significant difference between the realized average returns associated with certain characteristics of securities, or on portfolios of securities formed on the basis of those characteristics, and the returns that are predicted by a particular asset pricing model. What is anomalous with respect to one model may be consistent with the predictions of other asset pricing models. For example, an excess return associated with a security’s dividend yield is anomalous with respect to the basic Capital Asset Pricing Model but is consistent with extensions that incorporate investor taxes. Some anomalies are inconsistent with any known rational asset pricing model; they appear to represent “money left on the table”; such examples include the

Citations