Credit spreads rise after a monetary policy tightening, yet spread reactions are heterogeneous across firms. Exploiting information from a panel of corporate bonds matched with balance sheet data for U.S. non-financial firms, we document that firms with high leverage experience a more pronounced increase in credit spreads than firms with low leverage. A large fraction of this increase is due to a component of credit spreads that is in excess of firms' expected default. Our results suggest that frictions in the financial intermediation sector play a crucial role in shaping the transmission mechanism of monetary policy.