The stress test of the European Central Bank has become one of the primary regulatory tools for the European banking system. In order to make such a regulatory indicator, different national banks need to be commensurated. They need to be made comparable according to a common metric. Despite a substantial literature, little empirical work has been done to further our understanding of the social and political processes through which these indicators are made. We use Actor-Network Theory (ANT) to enrich the existing literature with an in-depth account of how commensuration is negotiated. We find that despite a preference for commensuration, regulators allow ‘incommensurable’ categories to exist due to largely unrecognised regulatory benefits.