This research aims to verify if the information supplied to the stock market on the intention of adhesion to the Differentiated Levels of Corporate Governance on the São Paulo Stock Exchange generates abnormal returns in the stock prices of these companies. Adherence to this market is expected to result in the growth of company image, negotiability of its papers and the amount of information disclosed to its investors. An event study, based on the assumptions of MacKinlay (1997), was used for the empirical research, with a sample of 18 companies that send the relevant information to the market. Non-parametric regression was applied to test the parameters of the market model of the event study. This tool was taken from the bibliography by Dombrown, Rodriguez and Sirmans (2000) and Lima (2005). The results of the event study demonstrated no abnormal returns in the prices of the companies stocks, demonstrating that information about adherence to the Differentiated Levels of Corporate Governance on the São Paulo Stock Exchange was not important for the market. Despite the results and conclusions, some research limitations must be taken into account, such as: the conclusions were been restricted to the sample, the variable and the econometric tool.
Event Study; Efficient Markets Hypothesis; Corporate Governance
