Produced in the 1970s, the theory o

Produced in the 1970s, the theory of asymmetric information discussed in a series of important influence in the asymmetric distribution of information between the two sides for incomplete transactions or market transactions and market generated operating efficiency. From the beginning of the 1980s, the introduction of the theory of financial markets research.Information asymmetry mainly includes three aspects: first, either none of the parties to the transaction to get completely clear message; second, information about the transaction between the parties to the transaction distribution is asymmetric, where one party than the other possession of more relevant information; third, the relative position of the respective parties to the transaction for possession in respect of information are clear, but the possession of the relevant information asymmetry leads before and after the transaction is completed in adverse selection and moral hazard problems.Asymmetric information leads to adverse selection and moral hazard, so that the transaction can not be achieved Pareto optimal. They seriously reduce the efficiency of the market, in extreme cases, even cause the market trading halt, making market transactions exist.