This article sheds light on the crisis of September 2019 by placing these events in the broader context of monetary policy normalization. It starts by recalling how the operational framework of the Fed evolved since the global financial crisis. Normalization principles, the issues that arose from them and the actual normalization process are then examined. This historical sequence is interesting because it provides insights on (1) the interplay between monetary policy and liquidity regulations and (2) the advantages and limitations of different operational frameworks (corridor vs. floor systems).