Investment Grade (IG)

The investment-grade label is a threshold, not just a descriptor. Many pension funds, insurance companies, and sovereign wealth funds operate under mandates — rules governing what they can own — that restrict them to investment-grade bonds. A bond rated BBB−, the lowest rung of IG, technically qualifies; a bond rated BB+, one notch lower, does not. This hard boundary means that a single-notch downgrade across that line can trigger large-scale forced selling, because institutional holders must exit positions that no longer meet their mandates.

Within the investment-grade universe, spreads still vary considerably. AAA-rated bonds trade at very tight credit spreads over government benchmarks, while BBB-rated bonds — the largest and fastest-growing segment of the IG market in recent decades — carry noticeably wider spreads. Investors and economists refer to BBB bonds as the "bottom of investment grade" and watch them closely during periods of economic stress, since they are most at risk of sliding into speculative territory.

Bonds that fall from investment grade to below-investment-grade status are called fallen angels; bonds that rise from below IG to IG status are called rising stars. The opposite end of the spectrum — below-investment-grade bonds — goes by several names: sub-investment grade, speculative grade, or colloquially, high yield or junk bonds. These carry wider spreads to compensate for greater default risk, reflecting the risk-on/risk-off dynamics that shape demand for lower-quality debt. See the bonds page for live data across rating categories.