An ideal gas approach to classify countries using financial indices

► We use the ideal gas analogy to describe the dynamics of world markets, using return series of world indices. ► A clear relationship is found between the B coefficient of the exponential function and the volatility in the financial indices. ► The proposed approach consists of an original method to classify countries based on just these two features of the market. ► The results are compared with classifications from traditional organizations, such as the World Bank, IMF and UN.