Um teste empírico sobre o preço das ações da Bovespa ao redor dos anúncios das demonstrações financeiras trimestrais

Abstract

This research aimed to test empirically the efficiency of the Brazilian stock market represented by the São Paulo Stock Exchange portfolio - São Paulo Stock exchange in a global crisis period, performed the announcements dates of the events that are the ITR's - the quarterly financial statements of the first quarter of 2008 until as the second quarter of 2009, made by event study s methodology representing better the semi-strong efficiency, it verified if had significant alterations in the stock prices, had been measured by the AR abnormal return, caused by the event announcement, where the AR significance was measured by the sign test, and its expected return measured by the CAPM Capital Asset Pricing Model. Therefore, the empirical test lead the conclusion the announcements had caused significant alterations in the stock prices, given the CAR - accumulated average abnormal returns behavior, had reacted as the expected one, then the CAR had reacted in compliance with of the good news classifications where represented 20% of the net profits increase of the company in relation the same period of the previous year, and for the bad news 20% net profits decrease, and for the classification of no news the companies that they had had the net profits nor over and nor below of 20% deviation. Thus the CAR sign test got the statistical of -3,27, out of the critical value of 1,64 to -1,64 of the normal distribution, indicating the Brazilian stock market adjusts the stock prices around the quarterly financial statements in global period of crisis, also indicating the semi-strong form of the efficient market hypothesis.