The U.S. stock market’s return during the first month of a quarter positively predicts the second month’s return, which then negatively predicts the first month’s return of the next quarter. The pattern arises from a model in which investors do not fully recognize that earnings announced in the second month of a quarter are inherently similar to those announced in the first month, thereby overreacting to such predictably repetitive earnings. The same pattern exists in the cross-section and time series of industry returns. Evidence from survey data lends support to the mechanism of correlation neglect.