This paper examines the impact of divergence between accounting standards and banking regulation – for example, when banks’ assets are marked-to-market for regulatory purposes but not for accounting purposes. I build a model that examines divergence in connection with risk-management by banks. The model shows that divergence results in a risk-management trade-off – using derivatives to hedge has regulatory benefits but accounting costs, or vice versa. Banks thus hedge to a lesser extent. Hence, a negative shock is more likely to make banks insolvent. More generally, the model identifies a mechanism by which divergence can have undesirable “real effects.”