This paper reviews the literature on IPO s abnormal initial return(AIR) from the perspective of under-pricing in the primary market and overvaluation in the secondary market and gives a different explanation about China s IPO s AIR.

IPO s abnormal initial return has puzzled scholars for many years.

Study on Noise Traders and the Real Initial Returns of Initial Public Offerings in China

This paper focuses on the real initial return of the cash purchase and analyzes its rationality and influencing factors.

The result shows that the announcement of seasoned equity offering in advance causes negative abnormal return of the share price of listed companies and also shows the low degree of market identification of seasoned equity offering of listed companies.

We take abnormal return as the main topic of this paper.

According to the hypothesis of weak-form market efficiency ,it is impossible for the investor to gain abnormal return by making use of out-dated price information .

In a forecast view,the estimated betas used by a single-index model which is based on total returns is completely proxy for that used by a single-index model which is based on excess returns and is based on theoretical foun.

Event study method is adopted to conduct empirical research of the IPO abnormal returns of new listed stocks in China.

It is found that issuing price,turnover rate on the first listed day,size of money raised,issuing P/E ratio and market index,have significant impact on the abnormal returns of shares on the first listed day,whereas,the influence of net asset per share before issuance,real negotiable share rate after issuance,method of issuance and the reform of split share structure,is unobvious.