Thesis (M.Sc.)--Chulalongkorn University, 2009

This research investigates the relationship between abnormal return from insider trading and corporate governance. It also tests whether insiders earn higher abnormal returns from trading stocks prior to earning announcements than the other periods. The samples of the study are all insider trades filed with Security Exchange Commission during the year 2006-2007. This research has found asymmetric relationship between corporate governance and abnormal return from insider trades. For insider sales, there is negative relationship between corporate governance and abnormal return. For insider purchases, there is positive relationship between corporate governance and abnormal return. Next, this study has found that insider trades prior to earning announcements yield significantly higher abnormal return than trades occurring during other periods. Thus, blackout period regulation which prohibits any insider trades during the period prior to firms’ earning announcements should be valuable to Thai capital market.