TL;DR. Investment grade and high yield are the two main credit buckets in the corporate bond market. The split is drawn by credit ratings — BBB− / Baa3 and above are investment grade, BB+ / Ba1 and below are high yield (“junk”). High yield bonds pay more because they default more often. The question every credit investor has to answer is whether the extra yield is enough to compensate for the losses.
What “Investment Grade” and “High Yield” Actually Mean
When a company borrows in the bond market, the three big credit rating agencies — Standard & Poor’s, Moody’s, and Fitch — assess how likely the issuer is to repay. They publish a letter grade that summarizes that risk. The published rating scales from all three agencies divide the ladder in two:
- Investment grade (IG) runs from AAA / Aaa at the top down to BBB− / Baa3.
- High yield (HY) — also called speculative grade, sub-investment grade, or “junk” — starts at BB+ / Ba1 and runs down to D (default).
That line matters because banks, insurance companies, and many pension funds are restricted by regulation or by their own investment policies from holding more than a token allocation of high yield. A downgrade from BBB− to BB+ can therefore force a wave of forced selling that has nothing to do with the bond’s actual risk on day one. Bonds that get pushed across the line are called fallen angels — bonds that were investment grade at issue and have since slipped below the boundary.
The SEC’s investor education portal puts the distinction simply: investment-grade bonds are “considered more likely than non-investment grade bonds to be paid on time,” while non-investment grade bonds “generally offer higher interest rates to compensate investors for greater risk.”
The Yield You Earn — and the Spread That Pays You
Two numbers describe a corporate bond’s pricing:
- Yield — what the bond pays per year if held to maturity, expressed as a percent.
- Spread — how much extra yield the bond pays over a comparable-maturity US Treasury.
Spread is the cleaner risk measure. A 5-year corporate bond yielding 6.5% when 5-year Treasuries yield 4.5% has a spread of 200 basis points (bps), or 2.00%. That spread is the market’s compensation for credit risk (the chance the issuer defaults), liquidity risk (the chance you can’t exit), and any embedded options (whether the bond can be called early).
A refined version called option-adjusted spread (OAS) strips out the call and put options embedded in the bond, leaving a cleaner read of pure credit and liquidity compensation. OAS is the spread measure that most professional bond investors actually track. Over long stretches, IG OAS has typically run between 100 and 200 bps, while HY OAS has averaged closer to 500 bps. Both spike sharply in crises and compress when the credit cycle is calm.
The Risk You Are Compensated For — Defaults and Recoveries
The reason high yield bonds yield more is that high yield bonds default more.
Default rates climb sharply down the rating ladder. Moody’s published 5-year cumulative default rate data shows the dispersion clearly: 0.18% for Aaa, 0.28% for Aa2, 2.11% for Baa2 (the lowest investment-grade tier), 8.82% for Ba2 (mid high-yield), and 31.24% for B2 (Moody’s study summarized by Wikipedia).
In other words, a portfolio of B2-rated bonds should expect roughly one in three to default within five years on average. The yield premium has to cover that, plus a return.
Long-run high yield default rates have averaged about 5% per year over the cycle, per data summarized in Wikipedia’s high-yield bond entry. During the COVID-19 shock, that figure briefly rose to just under 9%.
Recovery isn’t zero. When a bond defaults, holders typically recover something — often around 40% of face value for senior unsecured corporate bonds, more for secured paper, less for subordinated. So the expected loss math is roughly:
Expected annual loss ≈ default rate × (1 − recovery rate)
A 5% annual default rate at a 40% recovery rate works out to roughly 3% in expected credit losses per year. That is the threshold the spread has to clear for high yield to compensate investors over Treasuries on a long-run, loss-adjusted basis.
A Simple Worked Example
Suppose 5-year US Treasuries yield 4.5%. A BBB-rated corporate bond yields 5.5%, giving a 100 bp spread. A B-rated high yield bond yields 8.5%, giving a 400 bp spread. Plug in long-run averages:
| Bond | Yield | Annual Default Rate | Recovery | Expected Loss | Net Expected Return |
|---|---|---|---|---|---|
| 5y US Treasury | 4.5% | ~0% | 100% | ~0.0% | ~4.5% |
| BBB corporate | 5.5% | ~0.4% | 40% | ~0.24% | ~5.26% |
| B-rated HY | 8.5% | ~6% | 40% | ~3.6% | ~4.9% |
The punch line: a 400 bp HY spread barely beats the Treasury after losses on these assumptions. When credit spreads are tight, high yield investors can be paid almost nothing for taking real default risk. When spreads are wide — like the levels seen briefly in late 2008 and March 2020 — the math swings sharply the other way.
How Default Risk Scales Across the Ladder
The chart above is the single most important picture in credit investing. The default rate is not linear with rating — it is roughly exponential. Moving one notch across the IG / HY boundary (Baa2 to Ba2) more than quadruples the 5-year default rate. Moving from Ba2 to B2 more than triples it again. That non-linearity is exactly why bond investors care so much about credit ratings at all.
The Rating Ladder Visualized
The ladder makes it clear why the BBB− / Baa3 line is so consequential in practice. Above it, default rates are low, regulated investors hold the bonds in size, and spreads stay tight. Below it, the buyer base shrinks, liquidity thins, and spreads have to compensate for genuinely material default probabilities.
Common Mistakes
- Chasing yield without checking spread. When HY yields are elevated because Treasury yields are elevated — not because spreads are wide — investors are not actually receiving extra credit compensation. The spread, not the headline yield, measures credit reward.
- Ignoring duration. Both IG and HY bonds carry interest-rate risk on top of credit risk. A 10-year IG bond can lose more in a rate selloff than a 2-year HY bond.
- Assuming defaults are uniform across vintages. Default rates are heavily cyclical. The long-run 5% HY default rate masks years that are well under 2% and crisis years that have run above 10%.
- Forgetting recovery. A 60% loss-given-default assumption is more accurate and more conservative than assuming default means zero. Recovery dispersion across the capital structure (senior secured vs subordinated) is large.
- Fallen-angel risk hidden inside “safe” IG portfolios. A BBB-rated bond that gets downgraded one notch lands in HY and may be sold by index funds and rating-constrained holders with no discretion, locking in a loss for the original investor.
What to Learn Next
- Credit default swaps (CDS). Derivative contracts that let investors buy or sell protection on a specific issuer’s default risk.
- Collateralized loan obligations (CLOs). Pools of leveraged loans tranched by credit risk — the structured-credit cousin of HY bonds.
- Leveraged loans. Senior secured floating-rate debt that sits between investment-grade bonds and high-yield bonds in many capital structures.
- Distressed and special-situations investing. Buying deeply discounted bonds where the investment thesis is about recovery through restructuring rather than coupon income.
Sources
- SEC Office of Investor Education and Advocacy: Bonds or Fixed-Income Products
- Wikipedia: Bond credit rating — S&P, Moody’s, and Fitch rating scales
- Wikipedia: High-yield debt — long-run HY default rate of about 5%, COVID-era spike to just under 9%, US HY market size
- Wikipedia: Corporate bond — market structure, IG/HY classification, institutional buyer restrictions
- Wikipedia: Credit rating agency — Moody’s 5-year cumulative default rates by rating
- Wikipedia: Yield spread — credit spread and option-adjusted spread definitions
Disclosure: This article was produced with AI assistance and reviewed before publication. It is for informational purposes only and is not investment advice.