This research focuses on reverse stock split event study. We are trying to identify the stock returns behavior on the days before and following the reverse split announcements. The sample of this study is reverse stock split events on Indonesia stock market between the year of 2002-2018. The abnormal stock price movement before the announcement shows a sign of insider trading existence and the abnormal stock price movement following the announcement shows a slow market adjustment to a particular new information. We are using cumulative abnormal return, cumulative market adjusted return, and market adjusted different return prior and post announcement in identifying the abnormal stock price movement

Finance, Event Study, Reverse Stock Split, Insider Trading, Efficient Market

• Theresia Lesmana, S.E., M.Ak., CertDA

• Edwin Hendra, S.Tp., M.M.

• Sasya Sabrina, S.E., M.M., CPSAK.