Direct Answer
The approximate percentage change in a bond's price for a 1 percentage point change in its credit spread, holding the benchmark curve unchanged. It isolates credit-spread risk from interest-rate risk. A higher spread duration means a bond or portfolio loses more value when credit spreads widen.
Spread Duration: Formula, Meaning, Signals, Examples and How to Use It
How Is Spread Duration Calculated?
The approximate percentage change in a bond's price for a 1 percentage point change in its credit spread, holding the benchmark curve unchanged. It isolates credit-spread risk from interest-rate risk.
Formula: Price change % approx = -spread duration x change in spread
Inputs:
- Spread duration in years
- Change in credit spread in decimal terms
Worked example. A bond with a spread duration of 4.2 whose spread widens by 25 basis points (0.25%) is estimated to change in price by -1.05%. The inputs are illustrative numbers, not market data.
Reading it. A higher spread duration means a bond or portfolio loses more value when credit spreads widen. A floating-rate bond can have low interest-rate duration but high spread duration.
Limits. It is a linear approximation that ignores convexity and assumes a parallel spread change across the position. It does not capture the risk of default itself, only of spread repricing.
What is Spread Duration?
The approximate percentage change in a bond's price for a 1 percentage point change in its credit spread, holding the benchmark curve unchanged. It isolates credit-spread risk from interest-rate risk.
How to use Spread Duration
A higher spread duration means a bond or portfolio loses more value when credit spreads widen. A floating-rate bond can have low interest-rate duration but high spread duration. A reading alone is never a buy or sell signal; it needs context from price structure, volume, volatility and the broader market regime.
Strengths
- It is specific to credit spread moves, so a portfolio's exposure to spread widening can be tallied separately from its rate exposure.
- A spread duration for each position lets portfolio spread risk be broken down by sector, rating bucket or issuer by summing weighted exposures.
- Reproducible when the formula and data convention are fixed.
Weaknesses and limitations
- A floating-rate note can have large spread duration yet near-zero interest rate duration, so the two figures must not be read as substitutes.
- Spread changes are often correlated with yield changes, so applying spread duration alone to a scenario leaves out the rate move occurring with it.
- Correlated indicators can create false confidence by repeating the same underlying information.
Editorial and risk note
This page is educational content, not individualized investment advice. It should not imply guaranteed prediction, accuracy or outperformance.
Frequently Asked Questions
Is Spread Duration a buy or sell signal?
No. A higher spread duration means a bond or portfolio loses more value when credit spreads widen. It is a linear approximation that ignores convexity and assumes a parallel spread change across the position. A trade built on it still needs a trigger, an invalidation rule, a position size and realistic execution assumptions.
What is the best setting for Spread Duration?
Spread Duration is computed from spread duration in years; change in credit spread in decimal terms, so the choices that matter are the data convention and the window it is read over. Test those across instruments, regimes and out-of-sample periods instead of fitting one historical winner.
Can Spread Duration be used by itself?
It is a linear approximation that ignores convexity and assumes a parallel spread change across the position. It does not capture the risk of default itself, only of spread repricing. For that reason it is read next to measures of direction, participation, valuation, liquidity and risk, not alone.
Does Spread Duration work on every timeframe?
The calculation (Price change % approx = -spread duration x change in spread) can be run on any bar size, but behavior is not portable: a reading on a five-minute chart describes a very different market window from the same reading on a daily chart. Validate the exact timeframe before relying on it.
Why does Spread Duration give false signals?
A floating-rate note can have large spread duration yet near-zero interest rate duration, so the two figures must not be read as substitutes. Spread changes are often correlated with yield changes, so applying spread duration alone to a scenario leaves out the rate move occurring with it. Lag, noise and regime changes add to this, because market participants react to new information after the reading is calculated.
How should Spread Duration be backtested?
Rebuild Spread Duration from spread duration in years using point-in-time data, write the rules before testing, include delisted securities where relevant, model realistic fills and costs, reserve a validation sample and compare with a simpler baseline.