The Shangai Composite Index dropped 20 points or 0.50 percent on Thursday to close at 3927 points. Losses were led by Aluminum Corporation of China (-5.63%), Zijin Mining (-4.14%) and Greenland Holdings (-3.70%). Offsetting the fall, top gainers were Datang Intl (10.02%), Bank Of China (2.06%) and Agricultural Bank of China (1.55%).