The volatility has a great influence on agents' decision-making, therefore, measuring the degree and effect of the determining factors of the stock market indicator is of paramount importance. The study, based on the premise that assets with greater weight in the portfolio, as well as the foreign currency (dollar) quotation, can serve as predictors to assess the volatility of the indicator. For this purpose, an error correction model - VEC was used, starting from four explanatory variables defined and theoretically supported. The results show the importance of the autoregressive method, which is manifested by means of significant statistics to explain the variation and direction of Ibovespa. Although the importance of oil, iron ore and the dollar are determining variables, other factors such as cooperation agreements and / or stimuli aimed at the recovery of the economy cannot be neglected.