What does a negative basis between CDS spreads and bond spreads mean, and how can investors exploit it?

Question

AcadiFi · Accepted Answer

The basis in credit markets is defined as:

**Basis = CDS Spread - Bond Spread (Z-spread or ASW spread)**

A **negative basis** means the CDS spread is below the bond spread — protection costs less than the credit risk embedded in the bond yield. This creates a theoretical arbitrage opportunity.

**The Negative Basis Trade**

Buy the bond (earn the high spread) + Buy CDS protection (pay the low spread). The net carry is positive because the bond spread exceeds the CDS premium.

**Worked Example — Stanfield Capital's Trade on Hargrove Corp:**

| Component | Spread |
|---|---|
| Hargrove 5-year bond Z-spread | 285 bps |
| Hargrove 5-year CDS | 220 bps |
| **Basis** | **-65 bps** |

Stanfield buys $10 million par of Hargrove bonds and buys $10 million notional of CDS protection.

Annual carry: ($10M x 2.85%) - ($10M x 2.20%) = $285,000 - $220,000 = **$65,000 positive carry**

If Hargrove defaults, the bond loss is covered by the CDS payout. If Hargrove survives, Stanfield earns the 65 bps spread difference.

**Why Does a Negative Basis Arise?**

1. **Bond-specific illiquidity** — the bond may trade at a discount due to poor liquidity, widening its spread beyond fundamental credit risk
2. **Supply/demand imbalances** — heavy bond issuance pushes bond spreads wider while CDS demand remains stable
3. **Funding costs** — the bond must be financed (repo or balance sheet), adding implicit cost not reflected in the spread
4. **Counterparty risk** — the CDS protection is only as good as the protection seller's creditworthiness
5. **Restructuring basis** — CDS contracts may use different restructuring definitions than assumed in the bond spread

**Risks — Why It Is Not a Free Lunch:**

| Risk | Impact |
|---|---|
| Funding rollover | If repo rates spike, the carry advantage disappears |
| CDS counterparty default | Protection fails exactly when needed |
| Mark-to-market | Basis can widen further before converging |
| Bond-CDS mismatch | Maturity, coupon, and restructuring terms may not perfectly match |
| Liquidity | Unwinding either leg during stress is costly |

**Key Exam Points:**

1. A negative basis is more common during periods of market stress (e.g., 2008-2009 saw massive negative basis).
2. The trade is NOT a pure arbitrage — funding, counterparty, and basis risks are real.
3. A positive basis (CDS spread > bond spread) is more common in normal markets.
4. Negative basis trades are popular with banks that can fund bonds cheaply on their balance sheets.

Explore credit derivative strategies in our CFA fixed income course.

What does a negative basis between CDS spreads and bond spreads mean, and how can investors exploit it?

Master Level II with our CFA Course

Related Questions

Practice Questions