Assimetria informacional e eficiência semiforte do mercado

Abstract

This study aimed to investigate the informational asymmetry in the Brazilian Stock Market, either upon calls for Ordinary General Assemblies or Board Meetings intended to increase capital through underwritings, or upon announcements communicating the decision of capital increase. Therefore, the semi-strong efficiency and the informational asymmetry of the market were verified. The data were obtained through the Stock Exchange and the database of the consulting firm, Lafis. Based on theoretical and empirical research, it investigated the existence of abnormal returns upon the announcement of new underwritings, and also the existence of abnormal returns accumulated for a previous period (–20 days) and a later period (+20 days), in relation to the date of the announcement. The results of the research suggest not only the existence of informational asymmetry in the Brazilian Stock Market but also the absence of semi-strong efficiency in the market.