Research On The Influence Of Research Report Rating Adjustment On Stock Market

Since the development of China’s securities market,the research business has developed rapidly,and the number of research institutes and analysts has grown rapidly every year.After the research,analysts’ research reports have become very important information products exported to the market.Analysts have become an important part to understand the market information asymmetry.The academic research on the impact of rating adjustment mostly uses the method of building portfolio,using rating adjustment to adjust positions,so as to calculate the cumulative abnormal return rate to explain the changes of rating adjustment on the market.Among them,the study of star analysts found that the effect of star analysts is strong,and can significantly boost the impact of stock prices.There are studies of different economic periods and market styles in foreign countries.It is found that in the US market,analysts’ rating adjustment is more effective in the bear market.In this paper,we find that in light industry sector,the influence of upward adjustment is greater than downward adjustment,the influence of bull market rating adjustment is greater than that of bear market,and the influence of bull market rating adjustment will make the yield reverse in the window period.According to the linear regression and probit model,the influence of standardized rating is lower than that of rating adjustment,and the influence of analysts’ efforts is greater than that of star analysts.Institutional reputation has more market influence than star analysts,and the influence of rating adjustment is greater in bull market.Finally,through the analysis of IC method,it is concluded that investors should pay attention to the changes of market value,institutional shareholding and market uncertainty to adjust investment strategy in the short term after rating adjustment.