Abstract: The Member States of the European Union have transferred to it the substantial scope of the domestic competence in financial sphere. So, the EU exclusive competence covers the monetary policy of the Member States whose currency is the euro. Besides that, the legal regulation of the activities in the banking, insurance and stock markets are largely performed from the EU level. The European Union is not a member of many international financial institutions that determine global financial legal order in the modern world. Moreover, until now there is no established procedure for EU Member States coordination in such institutions. Based on systemic and comparative legal methods, the article explores peculiarities of realization of the EU external competence. The author concludes that development of financial integration in the European Union will inevitably lead to development of the legislation that would clearly regulate the procedure of EU Member States coordination in the international financial institutions. It would further limit legal capacity of the Member States and would result in so called “Europeanization” of the international financial legal order. Brexit would enhance this process.