What explains regulators\u2019 preferences concerning the Single Supervisory Mechanism (SSM)? The paper answers this question by providing an alternative account of the creation of the SSM using an institutionalist perspective. It is argued that the creation of the SSM does not simply reflect the material interests of governments and domestic financial firms, but that regulators\u2019 positions were also significantly affected by the institutional environment in which they operated. Two characteristics of domestic supervisory governance are identified: the institutional responsibilities of banking regulators (microprudential and/or macroprudential) and the fragmentation of supervisory and monetary policies. The empirical analysis demonstrat...