This paper investigates the abnormal return pattern around large shareholders' sales based on disclosed trading data before March 31, 2008. We have found that cumulative abnormal return (CAR) was 4.12% before sale and -2.61% after sale respectively. This reveals that large shareholders time sales successfully and make abnormal profit, whilst outside investors regard large shareholders' sales as bad news and respond negatively. On the date of disclosure, investors react more negatively to larger sales, bad performance companies and privately owned companies. Even long after the disclosure, investors respond negatively especially to those firms which have poor performance or have been sold by controlling shareholders. The results of the investigation show that large shareholders have made use of their information advantage to gain lofty trading profit, and the prominently large CAR before sale provides strong evidence for strengthening regulation.