Abstract: Based on insider trading and manipulations in China securities market during 1993 to 2000,using event studies,adjusted model proposed by Meulbroek(1992)and cross section test,the paper compares information content of insider trading with market manipulation.It is found that aggregate econometric result of insider trading is different from sub-sample’s,and Meulbroek(1992)overrates the information content of insider trading.Meanwhile the information content of manipulation is very significant.Moreover,different data and more detailed trades are used in order to get robust result.We find that insider buying cannot get abnormal earning and insider selling gives wrong signal to the market.We also find pure market manipulation and manipulation buying based on insider information cause significant response in the market.At the end,some policy suggestions of regulation on insider trading and manipulation are put forward.

Key words: insider trading, market manipulation, information content, abnormal earning