O balanço anual 2014 da Petrobras e a eficiência do mercado acionário no Brasil: um estudo de evento

• Ano de defesa: 2016
• Autor(a) principal: Faria, Andrei Francalacci de Castro
• Orientador(a): Pessoa, Marcelo de Sales
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Estudo de eventos; Balanços da PETROBRAS; Retornos anormais; Modelos de precificação; Hipótese de Eficiência do Mercado (HEM); Operação Lava Jato; PETROBRAS
• Palavras-chave em Inglês: Event study; Earnings announcements; Abnormal returns; Efficient market hypothesis
• Link de acesso: https://hdl.handle.net/10438/16629

We studied the effects on Petrobras shares arising from the presentation of the earnings announcements of 2014´s third and fourth quarter, the first announcements made after the beginning of the corruption investigation called Operação Lava Jato. We evaluate the impact on prices of the company's stocks with an Event Study. As a control, we analyzed the effects of the disclosure of 1,152 quarterly earnings announcements on other 48 stocks that are part of the IBOVESPA´s theoretical portfolio in the period between 2010 and 2015. We seek to identify the presence of abnormal returns and verify that all information is automatically transferred to prices, suggesting the semi-strong efficiency of the Brazilian stock market in accordance with the Market Efficiency Hypothesis (EMH) developed by Fama (1970). At the end we compare the results of the two specific earning announcements studied with the observed results of other earnings announcements of Petrobras. No evidence was found of market efficiency during the 2010-2015 period neither for the group of 48 stocks, NÃO_PETRO, nor for the PETRO group, formed by the two Petrobras shares. We then analyzed the results in two periods. The first, called Bonanza (2010-2013), showed the same results as the 2010-2015 period, with no significant abnormal returns in the event window [0,1]. The results of the Crisis period (2014 -2015) showed that the information of the earning announcements ha a statistical significant impacted on the prices of the studied stocks. To analyzing the results of the individual earning announcements of Petrobras, we identified the need for additional information, extrapolating the scope of an event study.