on the other hand, for those stocks with earnings substantially below the previous year, there was no systematic market reaction after the announcement as the CAAR remained relatively stable.
ball reviews over 20 different studies which reported abnormal returns, and agrees that taken at face value, studies of the market reaction to earnings announcements reveal post-announcement excess returns
however, he argues that the results of these studies are probably not due to market efficiency, but rather to methodological errors and to a specification of the model that generates security returns