How do I isolate spread duration from rate duration in a credit portfolio?

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AcadiFi · Accepted Answer

Isolating spread duration from rate duration is the cornerstone of pure-credit positioning. The goal is a portfolio whose P&L is driven by credit spread changes while Treasury rate movements net to zero. Construction approach: 1. Identify target credit exposure. Example: overweight BBB industrial names totaling $200M with spread duration of 6.5 (meaning 1 bp spread tightening gains $130K). 2. Compute the rate duration of that exposure. A BBB 10-year bond with spread duration 6.5 has rate duration roughly 7.2 (modestly higher because spread duration and rate duration are close for investment grade). 3. Short Treasury futures to neutralize the rate duration. Using 10-year Treasury futures with DV01 around $75 per contract, the hedge ratio is: Contracts = (Portfolio rate DV01) / (Futures DV01) = ($144K) / ($75) = 1920 contracts short 4. Rebalance as prices change. The hedge ratio shifts when yields move, spreads move, or positions change. Weekly rebalance is typical. ```mermaid flowchart TD A[Buy BBB Bond
$200M] --> B[Long Rate + Spread
DV01] C[Short 10Y Futures] --> D[Short Rate DV01] B --> E[Net] D --> E E --> F[Zero Rate
Pure Spread] ``` P&L attribution after hedging: - Spread tightens 10 bp → bonds gain $1.3M (spread duration × spread move × notional) - Treasury yields fall 5 bp simultaneously → bonds gain $720K from rates, futures lose $720K → net zero from rates - Total P&L: $1.3M purely from credit Example — Redwall Credit Opportunities hedged their BBB overweight throughout 2024. Without the hedge, Q3 P&L would have been +$8.2M (rates rally of 30 bp dominated). With the hedge, Q3 P&L was +$1.1M from credit alone — exactly the targeted credit exposure. Caveats: - Futures DV01 shifts with yield level; recalculate regularly - CTD (cheapest-to-deliver) shifts alter futures hedge behavior - Spread duration estimates differ between empirical and analytical methods - Cross-sector hedge breakdown: a sovereign hedge may not neutralize corporate curve moves when curves diverge Advanced variants use multiple futures (ED, FV, TY, US) to match key rate profile, not just total duration.

How do I isolate spread duration from rate duration in a credit portfolio?

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