Measuring information asymmetry surrounding earnings announcements

The primary objective of this research is to measure the information asymmetry before, during, and after earnings announcements and how it relates to the drift in post-earnings announcements over an extended period. The study uses the bid-ask spread as an information asymmetry proxy and employs a market model to assess daily data on Indonesia’s equity market before, during, and after the earnings announcement. Data were analyzed using the t test and least squares regression. The study provides empirical evidence showing that the bid-ask spread increases significantly before the earnings announcement, indicating information uncertainties between sellers and buyers. The findings show that the market reacts to accounting information indicated by a significantly reduced bid-ask spread soon after the market digests the information, following the concept of semi-strong market efficiency. The study shows a cumulative abnormal return and bid-ask spread strongly correlated a few days following earnings. However, the analysis found no long-term association between bid-ask spread and post-earnings announcement drift. The study found that stock market sellers and buyers use accounting data to set prices and that earnings releases reduce the bid-ask difference. The study suggests that the market regulator supports timely disclosure of this information.