From the Document: "U.S. companies are carrying record levels of debt to finance their operations and growth (Figure 1). Corporate debt largely consists of bonds and, to a lesser extent, leveraged loans, bank loans, and other liabilities. The Securities and Exchange Commission (SEC) is the primary regulator overseeing the debt capital markets. In recent years, financial authorities have become increasingly vocal about the buildup of the higher-risk portions of the corporate debt market. This Insight explains the market's composition and risks in the context of the current coronavirus (COVID-19)-induced capital markets stress."
Congressional Research Service: https://crsreports.congress.gov/