CDS-bond basis: comparing credit default swaps and bonds

A corporate bond is funded exposure: an investor pays a price, receives contractual cash flows, and bears the bond's credit and market risks. A credit default swap (CDS) is a separate derivatives contract. The protection buyer pays premiums and receives a contract-defined payment if a specified credit event occurs. Buying protection does not require owning the bond, so a CDS quote is not simply an insurance price attached to one security. {source:secCdsInterconnectedness2014}

A CDS spread and a bond spread can both respond to changing views about an issuer, but they come from different instruments, cash flows, counterparties, and trading venues. Their difference can help describe relative pricing. It cannot, by itself, tell you which market is correct or provide a direct default probability. {source:bisCdsCreditMarketsPrimer2002}

A CDS quote is often described as an annualized premium for a stated reference entity, seniority, currency, and maturity. Depending on the contract and market convention, a standardized running coupon can be paired with an upfront payment; the quoted market spread and the cash premium paid each quarter therefore need not be the same number. {source:isdaBigBangProtocol}

The bond side also needs a named measure. A yield-to-maturity spread over a government bond is not automatically interchangeable with an asset-swap spread, a par floating-rate bond spread, or a zero-volatility spread. Coupon, price, maturity, accrued interest, benchmark curve, and embedded options all affect the comparison. A useful basis analysis states which cash spread it uses and why.

This guide uses one explicit convention: CDS-bond basis = CDS spread − matched bond credit spread. Some publications or data vendors reverse the subtraction, so always check the definition before comparing a reported sign.

Suppose a hypothetical five-year CDS spread is 110 basis points and a closely matched bond's stated asset-swap spread is 140 basis points. On this convention, the basis is 110 − 140 = −30 basis points, called a negative basis. If the CDS is 140 and the bond spread is 110, the basis is +30 basis points. The numbers are hypothetical and the result depends on the chosen spread measures.

In a simplified negative-basis position, an institution buys a bond and buys CDS protection on a comparable notional amount. The bond supplies the issuer's spread exposure; the CDS is intended to offset much of the matched credit-event exposure. If the bond spread is 140 basis points and the comparable CDS premium is 110, their spread-equivalent gap is 30 basis points.

For $10 million of notional, 30 basis points times $10 million is about $30,000 per year of simple gross spread-equivalent arithmetic. It is not a forecast or a strategy return. Standardized CDS coupons, upfront payments, coupon dates, financing, repo, haircuts, collateral, transaction costs, taxes, and changes in market value can alter actual cash flows. A same-notional pair may also fail to neutralize the bond's and CDS's sensitivities exactly.

When the CDS spread is wider than the selected bond spread, the basis is positive under the stated formula. One might describe the protection as expensive relative to that cash-bond measure. A theoretical reverse position could involve shorting the bond and selling protection, but borrowing the bond, funding the short, managing collateral, and matching the contract can be difficult or costly.

The sign does not say that protection is mispriced. The bond may be unusually liquid or illiquid, a CDS may reference a broader set of obligations, or the quoted instruments may not have identical maturities, seniority, currencies, or optionality. A comparison is only as meaningful as its match and its execution prices.

A frictionless model suggests a close relationship between CDS premiums and credit spreads on comparable risky bonds. Actual markets are not frictionless. Bond and CDS bid-ask costs, different liquidity, repo specialness, funding rates, financing availability, capital use, balance-sheet limits, counterparty exposure, and risk compensation can all leave a persistent gap. The BIS documents thresholds for arbitrage in euro-area sovereign markets and finds that stress and volatility can raise the costs of closing the basis. That study is market- and sample-specific, not a universal threshold. {source:bisCdsBasisCosts2017}

The bond may require cash and financing for its full life while the CDS has a different margin and collateral profile. If a trade is crowded or a dealer cannot allocate balance sheet, a price difference may widen before it narrows. The ability to hold through interim losses and meet variation-margin or repo calls matters; theoretical convergence does not guarantee that a position survives to convergence.

A CDS responds to the credit events, obligations, seniority, and settlement provisions defined by its documentation; it does not pay merely because a bond's market price falls. Following a qualifying event, contracts may settle physically through delivery of eligible obligations or in cash using an auction price. The applicable definitions and process determine the result, including how restructuring is handled. {source:isdaCreditDerivativesGlossary} {source:dtccCdsCreditEvents2026}

A CDS can offset credit risk without removing interest-rate duration, liquidity, recovery, or spread risk. Bond and CDS sensitivities can differ even at the same notional. Uncleared bilateral contracts also create exposure to the counterparty; collateral or central clearing changes that exposure but does not make every funding, operational, legal, or liquidity risk disappear. {source:secCdsInterconnectedness2014}

Record the CDS reference entity, seniority, currency, maturity, documentation and restructuring terms, quote side, timestamp, running coupon, and upfront amount. On the bond side, record the exact issue, seniority, currency, maturity, price side, accrued-interest treatment, benchmark curve, spread measure, repo terms, and embedded options. Then state the basis formula and align observation times.

Use the result as a relative-value diagnostic, not a stand-alone trade signal. For related mechanics, read the bond spread-measures guide, the guide to corporate yields and Treasury moves, and clean versus dirty bond prices.