How Investors Trade Around Interim Earnings Announcements

: This study focuses on non‐institutional trading behaviour around interim earnings announcements in the emerging market. We separate the stock trading activity of Finnish households into five trading classes and compare the results to institutional trading. Data covering the years 1996–2000 shows that earnings news triggers trading in every trading class. We also find some evidence that actively trading individuals especially (compared to passively trading ones) show increased buying and selling activity before the event compared to the non‐event period. After the event we find that Finnish households in the most active investor class tend to follow a contrarian strategy, especially selling after good news. This adds to previous evidence by Grinblatt and Keloharju (2000b). Furthermore, the performance of the active investor classes is superior to that of passive ones. Finally, the institutional trading class is clearly less affected by the announcement than the active investor classes, suggesting that institutions utilize a broader information set than individual investors.