What is credit migration risk and how does a downgrade affect bond prices even without default?
For CFA Level I, I understand that default risk means the issuer doesn't pay. But my study materials also mention 'credit migration risk' as a separate concept. How does a rating change affect bondholders if the issuer is still making all its payments on time?
Credit migration risk (also called downgrade risk or credit transition risk) is the risk that an issuer's credit rating deteriorates, causing the bond's market value to fall — even though the issuer continues making all promised payments. It's one of the most practically important fixed income risks.
Why Downgrades Hurt Even Without Default
When a bond is downgraded, the market demands a higher yield (wider credit spread) to compensate for the increased perceived risk. Since bond prices move inversely to yields, the bond's price drops.
Numerical Example — Westbrook Manufacturing
Westbrook has a 5-year, 5% annual coupon bond outstanding. Currently rated A with a spread of 60 bps over the risk-free rate of 4.00%. The bond trades at par ($1,000).
Now suppose Westbrook gets downgraded to BBB, where the typical spread is 130 bps:
- Old yield: 4.00% + 0.60% = 4.60%
- New yield: 4.00% + 1.30% = 5.30%
- New price: PV of 5% coupons + $1,000 principal at 5.30% = ~$987.02 for a 5-year bond
The bondholder loses approximately $12.98 per bond (1.3%) from the migration alone — despite every coupon being paid on schedule.
Credit Transition Matrices
Rating agencies publish historical transition matrices showing the probability of moving from one rating to another over a given period. For example:
| From / To | AAA | AA | A | BBB | BB | Default |
|---|---|---|---|---|---|---|
| A | 0.05% | 2.1% | 89.3% | 6.8% | 1.2% | 0.08% |
This tells us an A-rated bond has about a 6.8% chance of migrating to BBB and a 1.2% chance of falling to BB within one year. Portfolio managers use these matrices to estimate expected credit losses and to price credit risk.
Types of Credit Events (Beyond Default):
- Rating downgrade (most common migration)
- Spread widening without a formal downgrade
- Placement on negative watch/outlook
- Covenant violations triggering higher spreads
Exam Tip: CFA Level I may ask you to calculate the price impact of a spread change after a credit migration. Always apply the new spread to the risk-free rate and re-discount all future cash flows.
Practice credit risk scenarios in our CFA question bank.
Master Level I with our CFA Course
107 lessons · 200+ hours· Expert instruction
Related Questions
What exactly is the Capital Market Expectations (CME) framework and why does it matter for asset allocation?
How do business cycle phases affect asset class return expectations?
Can someone explain the Grinold–Kroner model step by step with numbers?
How do you forecast fixed-income returns using the building-blocks approach?
PPP vs Interest Rate Parity for forecasting exchange rates — when do I use which?
Join the Discussion
Ask questions and get expert answers.