The article explains to what extent currency mismatch in banking and non-financial sectors determine vulnerability of Russian economy with respect to possible external shock. The authors explain how Central Bank of Russia exchange rate policy depends on currency mismatches and to what extent currency mismatches determined the slowdown of Russian economy during the financial crisis. The article shows the dynamics of currency mismatch from 2004 to 2012 year. The authors offer the model of the relationship between capital flight and external debt of private sector. The authors present the results of stress test of Russian economy. The stress test implies external shock similar to external shock of the end of 2008. According to stress test as of end of 2012 both banking and private sectors are less vulnerable to possible external shock. Meanwhile authors made a conclusion that vulnerability of a private sector remains unacceptably high. The authors recommend 2 ways how to decelerate the currency mismatch of a private sector.