In the context of the 2007-2009 financial crisis, central banks innovated in the form of multiple unconventional measures. Due to a different history, different mandates and monetary policy implementations, the first crisis measures, mainly for financial stability, differed between the Fed and the ECB, resulting in a balance sheet size and structure of the assets specific to each. After 2015, the ECB’s large-scale asset purchase transactions marked a convergence of the unconventional policies of the two central banks, which resulted in the ECB renouncing the principle of separation between monetary policy and stability financial. In addition, the risk-taker of last resort function of the two central banks has increased, although differences persist in their risk management policies (scope of counterparties and securities eligible).