Risk Relation and the Corporative Governance Practice in the Brazilian Stock Market: an approach according to the portfolio theory by Markowitz

ABSTRACT

This study examines whether there is a relationship between the risk of a portfolio that would be sufficiently diversified in the Brazilian stock market, made by companies classified in the IGC, in comparison with the Market Portfolio. For this purpose, a preliminary proceeding of the methodological research literature, documentary exploratory and subsequent research of the theoretical portfolio of the index shares differentiated corporate governance of BM&FBOVESPA valid for first, second and third quarters of 2009. Therefore, with the aid of the electronic spreadsheet Excel, being used with the model of Markowitz (1952) and of the methodology developed by Gonçalves Jr, Pamplona and Montevechi (2002), we have attempted to find the minimum variance portfolios for each quarter in order to test the hypothesis that there is a relationship between the risk of these portfolios, considered sufficiently diversified in the Brazilian stock market (according to the findings of Sanvicente and Bellato, 2004), composed by companies classified in the IGC. The results have indicated that these portfolios for the assets of IGC, are higher than the market portfolio, since they would have their risks represented by about 34%, 32% and 21% of risk IBOVESPA in its corresponding period in identical levels of return. Through the theory of diversification is possible to obtain an inverse relationship between risk and good corporate governance practices. Additionally, the IGC selected portfolio dominates the portfolio of the IGC and the Bovespa index, respectively, using the coefficient of variation, it has the lowest risk contained for each additional return.

Key words:
Corporate governance; Portfolio selection; Portfolio optimization