Made available in DSpace on 2014-12-17T13:53:30Z (GMT). No. of bitstreams: 1 RaimundaMLS_DISSERT.pdf: 638002 bytes, checksum: f4c7693a6b7a4b11a332a1d4e60703e4 (MD5) Previous issue date: 2010-09-20 / The financial crisis that occurred between the years 2007 and 2008, known as the subprime crisis, has highlighted the governance of companies in Brazil and worldwide. To monitor the financial risk, quantitative tools of risk management were created in the 1990s, after several financial disasters. The market turmoil has also led companies to invest in the development and use of information, which are applied as tools to support process control and decision making. Numerous empirical studies on informational efficiency of the market have been made inside and outside Brazil, revealing whether the prices reflect the information available instantly. The creation of different levels of corporate governance on BOVESPA, in 2000, made the firms had greater impairment in relation to its shareholders with greater transparency in their information. The purpose of this study is to analyze how the subprime financial crisis has affected, between January 2007 and December 2009, the volatility of stock returns in the BM&BOVESPA of companies with greater liquidity at different levels of corporate governance. From studies of time series and through the studies of events, econometric tests were performed by the EVIEWS, and through the results obtained it became evident that the adoption of good practices of corporate governance affect the volatility of returns of companies / A crise financeira ocorrida entre os anos de 2007 e 2008, conhecida como crise do subprime, colocou em evid?ncia a governan?a das empresas no Brasil e no mundo. Para monitorar o risco financeiro, ferramentas quantitativas de gest?o de risco foram criadas na d?cada de 1990, ap?s v?rios desastres financeiros. A turbul?ncia do mercado tamb?m tem levado as empresas a investirem no desenvolvimento e utiliza??o de informa??es, que s?o aplicadas como ferramentas de apoio aos processos de controle e tomada de decis?o. In?meros estudos emp?ricos sobre efici?ncia informacional do mercado t?m sido efetuados dentro e fora do Brasil, revelando se os pre?os refletem instantaneamente as informa??es dispon?veis. A cria??o de n?veis diferenciados de governan?a corporativa na BOVESPA, em 2000, fez com que empresas tivessem maior comprometimento em rela??o aos seus acionistas, com maior n?vel de transpar?ncia em suas informa??es. A proposta desse trabalho ? analisar como a crise financeira do subprime afetou, entre janeiro de 2007 e dezembro de 2009, a volatilidade do retorno das a??es na BM&FBOVESPA de empresas com maior liquidez em diferentes n?veis de governan?a corporativa. A partir de estudos das s?ries temporais e, atrav?s de estudos de eventos, foram realizados testes econom?tricos, atrav?s do EVIEWS, e pelos resultados apresentados tornou-se evidente que a ado??o de boas pr?ticas de governan?a corporativa influenciam a volatilidade dos retornos das empresas