How Naïve Is the Market’s Use of Firm‐Specific Earnings Information?

Recent studies suggest the apparent delay in the stock-price response to earnings announcements (i.e., post-earnings announcement drift) is caused by investors who underestimate the autocorrelation of seasonally-differenced earnings (persistence). I present results that suggest: (1) a firm's future persistence is predictable on the basis of its past persistence; (2) the immediate stock-price response to earnings is positively related to historical persistence; (3) post-earnings-announcement drift is independent of historical persistence; and (4) consistent with (2) and (3), the difference between a firm's current observed persistence and that implied in stock prices is independent of its historical persistence. These results extend prior research by demonstrating that investors are aware not only that seasonally-differenced earnings are autocorrelated, but that investors recognize firm-specific differences in the magnitude of the autocorrelation.