The Earnings Event-Time Seasonal and the Calendar-Time Seasonal in Stock Returns: Naive Use of Earnings Information or Announcement Timing Effect?

Abstract

We document a pattern in the day-of-the-week timing of future earnings announcements that is predictable from knowledge of the current quarter's earnings. The pattern mimics the predictable (+, +, 0, -) dependence previously reported in both seasonally differenced quarterly earnings themselves and in estimated abnormal returns at future quarterly earnings announcement dates (the “SUE effect”; see Rendleman, Jones, and Latané [1987]; Bernard and Thomas [1990]). The predictability of abnormal returns at future earnings announcement dates therefore is not independent of the well-documented day-of-the-week seasonal in stock returns (the “DOW effect”; see Osborne [1962]; Cross [1973]; French [1980]; Gibbons and Hess [1981]). Although the DOW effect is too small to fully explain the SUE effect, it appears to contribute to it, since both past SUE and current earnings announcement DOW are incremental in explaining announcement-day estimated abnormal returns. The unclear role of size and the presence of errors in estimating both unexpected earnings and its announcement day suggest caution in interpreting these results.