中文摘要：

本文以先发行H股后回归A股这一特殊交叉上市股票为研究对象，采用知情交易概率（PIN）度量信息不对称程度，研究股票交叉上市是否能降低信息不对称程度。对所有样本股票进行回归分析发现，交叉上市虚拟变量与PIN值负相关，即交叉上市会带来信息不对称程度的降低；并且，交叉上市股票的信息不对称程度要低于同期未交叉上市的股票。与过往文献不同，本文为此结论提供了一种全新的解释，交叉上市弓『起信息不对称程度降低是由于市场上“揭露”出来的信息更多，导致知情交易者的参与显著减少。最后，本文根据实证结果提出了相关政策建议。

英文摘要：

The main purpose of this study is to explore why cross-listing could reduce information asymmetry. This paper takes the special cross-listing stocks that issued H shares at first and then issued A shares as the sample, and measures the information asymmetry in the use of Probability of Informed Trading （PIN）. The results show that stocks have lower degree of information asymmetry after cross-listing. Moreover, compared with stocks which are not cross-listed, the PIN of the cross-listed stocks are also lower. The regression analysis reveals a negative relation between the cross-listing dummy variable and the probability of informed trading, which means cross-listing makes the degree of information asymmetry lower. The novel explanation is proposed with regard to the empirical results observed. The reason is that more information is revealed such that the arrival rate of informed traders decreases significantly. Finally, some policy suggestions are proposed based on the empirical results.