Stressed to the core: Counterparty concentrations and systemic losses in CDS markets

U.S. supervisory stress tests to date have focused on the resilience of large banks to withstand the direct effects of credit and trading shocks. Using data from Depository Trust & Clearing Corporation (DTCC), we apply the Federal Reserve's Comprehensive Capital Analysis and Review (CCAR) supervisory scenarios to evaluate the default of a bank's largest counterparty. We find that indirect effects of this default, through the bank's other counterparties, may be larger than the direct impact on the bank. Further, when taken as a whole, the core banking system has a higher exposure concentration to a single counterparty than does any individual bank holding company. We find that the U.S. banking system's counterparty exposure concentration has risen over the 2013-2015 period. Under the 2015 CCAR this corresponds to a market diversity with just over three counterparties under stress. Our results are the first to evaluate the U.S. credit derivatives market under stress and underscore the importance of a macroprudential perspective on stress testing.