Abstract: “The purpose of this study is to examine insider trading behavior reaction to news announcement by using firms listed on the Stock Exchange of Thailand (SET). The results show that the information content are significant to insider buys but not to insider sells. In other words,only insider buys are associated with abnormal returns. However, corporate news disclosures greatly impact insider sells. Trading before good news announcement shows significant abnormal return for both sells and buys, specifically, insider buys prior to good news significantly impact on stock prices.”

Keywords: insider trading, event study, abnormal return, Thailand