This paper aims to analyze the hypothesis that debenture issues generate positive abnormal returns in the shares of the issuing companies. For this purpose, a study of events is carried out between January 2014 and June 2015, based on the date of the announcement of the beginning of the distribution of the debentures. The study analyzes 40 pre-and post-conference sessions. The final sample is made up of 11 Brazilian non-financial companies. As a result, it can be verified that the majority of accumulated abnormal returns are positive and statistically different from zero, confirming the hypothesis of this study. This fact points to signals of semistrong market efficiency.