Credit quality has deteriorated within the investment-grade segment, where the share of bonds rated at the lowest investment-grade level has reached near-record levels. As of mid-2018, around 35 percent of corporate bonds outstanding were at the lowest end of the investment-grade segment, which amounts to about $ trillion.
In comparison, the share of high-yield bonds outstanding that are rated “deep junk” has stayed flat at about one-third from 2015 to 2018, well below the financial crisis peak of 45 percent.