In this study, the short-term fluctuations in the monthly returns on composite indexes of 17 emerging markets affected by the financial crises in the late 1990s and 2000 are decomposed with vector autoregressive estimates. The results are compared to the behaviour of variation in returns in developed markets. Three different models are estimated for each market. Due to first order autocorrelations, lagged returns contribute significantly to return volatility in emerging markets. Decomposition of variances indicates that dividend yield and interest rate are determining factors of volatility, but at varying degrees in different emerging markets. However, the role of dividend yield is not as strong as it is in the developed markets as efficient markets hypothesis would imply. In some cases, exchange rates significantly influence market volatility. Fluctuations in the world portfolio return have a small effect on return volatility in national markets. However, there are significant differences across all emerging markets that point to differences in market structures and particular conditions in each country. Significant contributions of interest rates, exchange rates and inflation imply the role of monetary and fiscal policy as precedents of financial crises.