Financial rating and behavior of actors in the financial market.

Summary The objective of this thesis is to analyze the role of rating agencies on the financial market. Our contribution consists in better understanding the influence of rating announcements on French equity market participants (investors and financial analysts).The first question concerns the informative contribution delivered by rating agencies and the impact of their decisions. In order to answer this question, we conducted a study of rating announcement events, distinguishing between announcements by nature, type and category.This research provides evidence that rating announcements have an overall impact on the equity market. The impact depends on the nature of the announcement, the information provided in the rating reports, the rating changes between categories and those made in the speculative category. Finally, the level of the rating depends on the financial and accounting characteristics of the rated firm.The second question concerns the beneficial role of rating agencies on the markets. In order to answer this second question, we conducted a research that consists in analyzing the evolution of information asymmetry between investors and liquidity around rating announcements.This research proves that positive (respectively negative) announcements lead to a decrease (respectively increase) of information asymmetry in the equity market. The results also prove that positive and neutral announcements, in contrast to negative announcements, lead to a reduction in price ranges and an improvement in trading volumes. These two concomitant effects reflect an improvement (respectively deterioration) in market liquidity during positive and neutral (respectively negative) announcements.The third question concerns the usefulness of rating announcements for analysts in their forecasts. In order to answer this question, we conducted research that consists of studying the evolution of the dispersion and error of analysts' forecasts around rating announcements.The results reveal an inverse relationship between the characteristics of financial analysts' forecasts and the nature of the rating announcement. The results show an inverse relationship between the characteristics of financial analysts' forecasts and the nature of the rating announcement. Positive and neutral announcements reduce the error and dispersion of analysts' forecasts.This research work attests to the real importance of the informational content of rating announcements for the equity market and the real contribution of the announcements to the improvement of financial communication in the market.