Chinese Stock Market Based On Private Placement Assets Acquired Events Semi-strong Form Effective Study

The subject of the paper is on the market efficiency of Chinese Stock Market. Judging a financial system is good or bad, the only criterion is the level of the efficiency of the system. As an important component of the financial sector, the role of the stock market to give full play relies on its effectiveness. We believe that the research of effectiveness of Chinese stock market has basic theoretical significance, but the research of the effectiveness of stock market is an empirical problem. This paper will focus on the empirical research of the market.After nearly 20 years of development, the efficiency of Chinese stock market has improved continuously. The research of our stock market efficiency level is also becoming more and more. At the same time, the EMH provide a good level of the tools, more and more Scholars use it research the efficiency level of the Chinese stock market. Most of the researches indicate that the Chinese stock has reached the weak-strong efficiency, but not reached the semi-strong efficiency. The discussion of the semi-strong efficiency is becoming the focus of the research.On the basis of the EMH , My research use the "event study" to positioning the efficiency of the Chinese stock market. The paper select 22 stocks in the Shanghai and Shenzhen exchanges in 2007 as sample to study the degree of the efficiency and to determine whether Chinese stock market has reached semi-strong efficient.From the empirical view of the paper, when listed companies targeted private offering of additional shares to purchase the assets, the accumulated surplus yield of the stocks is notable non-zero in the two days before the incident to the sixth day after, there is oscillation of the accumulated surplus yield after the two days of the incident, and the subsequent sharp rise in a situation of the phenomenon of the rapid decline that Chinese stock market advance information on the existence of the phenomenon of reaction, and there are incomplete information disclosure and market reaction over the case, which improve that the stock market in China has not reached semi-strong efficiency yetFrom the empirical results, we see that in order to improve the level of efficiency of Chinese stock market, we must improve information disclosure mechanism, increase the number of institutional investors; raise the level of ordinary investors and the ability of rational analysis, and reduce market speculation, and strengthen market supervision, improve the securities market regulatory system.