There appears to be a role for a theory of active portfolio management because O some portfolio managers have produced sequences of abnormal returns that are difficult to label as lucky outcomes. the "noise" in the realized returns is enough to prevent the rejection of the hypothesis that some money managers have outperformed a passive strategy by a statistically small, yet economic, margin. some anomalies in realized returns have been persistent enough to suggest that portfolio managers who identified these anomalies in a timely fashion could have outperformed a passive strategy over prolonged periods. some portfolio managers have produced sequences of abnormal returns that are difficult to label as lucky outcomes, and the "noise" in the realized returns is enough to prevent the rejection of the hypothesis that some money managers have outperformed a passive strategy by a statistically small, yet economic, margin. All of the