In this study, we focus on Malaysia, a developing economy where many firms are controlled by families. The sample is composed of acquisitions during the period 2000-2013. We find that on average acquiring firms neither create nor destroy long term values after controlling for the performance of a control group. This result shows that investors reacted rationally in valuing the bidding firms after the announcements of the completions of the acquisitions. Thus, at least in the long run performance of acquisitions, the capital market in Malaysia is informationally efficient.