This study examines whether the stock prices reflet the relevant information on the companies´current and potential credit ratings. This investigation was carried out from the construct of stock price synchronicity, that is, the more the stock prices reflect the specific information of a certain company, the less the synchronicity of these prices in relation to the market general information tends to be. It would imply that the stock prices tend to be more informative on the companies´potential in generating future economic benefit and on their risk levels. For carrying out this study, information on the companies which have their shares listed at the Brazilian Stock Exchange (Brazil, Stock Exchange and Over-the-counter – B3) from 2010 to 2015 were analyzed. The results obtained point that the stock prices not only embody information on the alterations of the companies´s current credit ratings regarding the upgrade, but also reflect, with certain antecipation, the potential credit ratings. Nevertheless, the results indicate that not every credit rating class is associated with relevant information for the capital market.