For many political economists, the loss of monetary sovereignty is the major reason why the Southern periphery fared so badly in the Euro area crisis. Monetary sovereignty here means the ability of the central bank to devalue the exchange rate or to buy government debt by printing the domestic currency. We explore this diagnosis by comparing three countries – Hungary, Latvia and Greece – that received considerable amounts of external assistance under different monetary regimes. The evidence does not suggest that monetary sovereignty helped Hungary and Latvia to stabilize their economies. Rather, cooperation and external assistance made foreign banks share in the costs of stabilization. By contrast, the provision of liquidity by the European Central Bank inadvertently facilitated the reduction of foreign banks’ exposure to Greece which left the Greek sovereign even more exposed. By viewing the Euro area as a monetary system rather than an incomplete state, we see that what is needed for Euro area stabilization is cooperation over banking union, rather than a fully-fledged federal budget.