Using US micro-level data on banks, we document a negative effect of high oil prices on US banks' balance sheets, more negative for highly leveraged banks. We set and estimate a general equilibrium model with banking and oil sectors that rationalizes those findings through the financial accelerator mechanism. This mechanism amplifies the effect of oil price shocks, making them non-negligible drivers of the dynamics of US banks' intermediation activity and of the US real economy. Macroprudential policy, in the form of a countercyclical capital buffer, can meaningfully address oil price fluctuations and reduce the volatility they cause in the US economy.