The paper by Eugene F. Fama challenges the literature on long-term return anomalies, arguing that market efficiency remains robust. Fama suggests that apparent overreaction and underreaction to information are equally common, and that post-event continuation of pre-event abnormal returns is as frequent as reversal. He emphasizes that most long-term return anomalies disappear when the methodology is changed, indicating that they may be methodological illusions. Fama also discusses behavioral models that attempt to explain overreaction and underreaction, finding that these models do not fully capture the range of observed anomalies. He concludes that the evidence against market efficiency from long-term return studies is fragile and that reasonable changes in the approach used to measure abnormal returns often suggest that apparent anomalies are due to chance. The paper highlights the importance of using appropriate models for expected returns and statistical methods to draw reliable inferences about market efficiency.The paper by Eugene F. Fama challenges the literature on long-term return anomalies, arguing that market efficiency remains robust. Fama suggests that apparent overreaction and underreaction to information are equally common, and that post-event continuation of pre-event abnormal returns is as frequent as reversal. He emphasizes that most long-term return anomalies disappear when the methodology is changed, indicating that they may be methodological illusions. Fama also discusses behavioral models that attempt to explain overreaction and underreaction, finding that these models do not fully capture the range of observed anomalies. He concludes that the evidence against market efficiency from long-term return studies is fragile and that reasonable changes in the approach used to measure abnormal returns often suggest that apparent anomalies are due to chance. The paper highlights the importance of using appropriate models for expected returns and statistical methods to draw reliable inferences about market efficiency.