Corporate bonds are a key source of funding for U.S. non-financial corporations and a key investment security for insurance companies, pension funds, and mutual funds. Distress in the corporate bond market can thus both impair access to credit for corporate borrowers and reduce investment opportunities for key financial sub-sectors. In a February 2021 Liberty Street Economics post, we introduced a unified measure of corporate bond market distress, the Corporate Bond Market Distress Index (CMDI), then followed up in early June 2022 with a look at how corporate bond market functioning evolved over 2022 in the wake of the Russian invasion of Ukraine and the tightening of U.S. monetary policy. Today we are launching the CMDI as a regularly produced data series, with new readings to be published each month. In this post, we describe what constitutes corporate bond market distress, motivate the construction of the CMDI, and argue that secondary market measures alone are insufficient to capture market functioning.