The purpose of this thesis is to determine if there are any significant abnormal returns arising when companies announces an upcoming rights offering on the Stockholm exchange. The thesis also considers possible reasons as to why the market react in different ways by examining the offerings’ underlying motives. The thesis adopts a quantitative approach, implemented by adeductive strategy. An event study has been used to study the market movements throughout the RO-announcement. The abnormal return is calculated according to the CAR-model which is later tested for its significance. A multiple linear regression is conducted in order to discover relations between the abnormal return and different independent variables. The main frame of theoretical reference is the Signalling Hypothesis as well as the Efficient Market Hypothesis. The study is also inspired by previous research on the subject, all of which are presented in the chapter. These include both recent and older studies on both American, Asian and European markets. Results conclude a significant negative abnormal return during the event window. There is a significant relationship between the underlying motive of the rights offerings and its abnormal return. However, no significant relationship can be stated between the frequency of the rights offering and its abnormal return. Underlying motive and frequency of RO’s explain theabnormal return by 10,11%.