Following the 2008-9 financial crisis, large banks increasingly issued contingent convertible bonds (CoCo bonds) to increase their capital buffers – a policy supported by national bank regulators. This paper examines if the issuance of CoCo bonds provides the same reduction in bank default risk as the corresponding issuance of common equity by analyzing the premium reduction in (single name) credit default swaps (CDS) around the corresponding issuance announcement events. We find that the default risk reduction associated with issuance crucially depends on the CoCo bond’s design features: Only CoCo bond designs with permanent writedown features provide a default risk reduction similar to equity. CoCo bonds with equity conversion features come with a lower subsequent volatility of the bank asset value, but are inferior to equity in terms of their default risk reduction.