Notes from the Desk: The Evolution of the Corporate Bond Market

Over the past 20 years, the corporate bond market has experienced a significant evolution driven by economic cycles, regulatory shifts, and changing investor demand. From the recovery following the early 2000s dot-com bubble through the global financial crisis, which spurred central bank interventions that resulted in low interest rates and record bond issuance and refinancing – the last two decades have seen a surge in demand for corporate bonds. Indeed, compared to 20 years ago, the investment grade (IG) corporate bond market grew by 308%, to reach a total market value of $6.6 trillion as of June 30, 2024. High yield (HY) corporate bonds grew by 131%, to reach a total market value of $1.3 trillion over the same period.

A common narrative around the corporate bond market is that investment grade corporate bonds have become lower quality over time, while high yield bonds have become higher quality. We looked at the ratings profile of the IG and HY universes to address those consensus narratives. We found that the IG universe has become lower quality in terms of ratings over the past 20 years, but only mildly, with a higher weight of AA, A, and BBB bonds coming at the expense of a shrinking AAA portion. High yield, on the other hand, can hardly be considered "junk" anymore as the universe has seen a significant shift higher in the portion of its highest quality tier, BB.

In the last two decades, the IG corporate market has grown by $5 trillion (to $6.6 trillion from $1.6 trillion in 2004), which is equal to the rate of 7.3% per annum. After the Great Financial Crisis, the AAA tier of the IG corporate bond market collapsed and has continued to remain a tiny part of the universe. Conversely, the AA, A, and BBB ratings tiers grew significantly, by $346 billion, $2.3 trillion, and $2.4 trillion, respectively.

Market value by rating of IG corporate bonds