Credit Relative Value Along the Issuer Curve

A single company usually has several bonds outstanding at once — a 3-year, a 5-year, a 10-year — each with its own credit spread over Treasuries. Plot spread against maturity for one issuer and you get that issuer's credit curve. Most of the time it slopes smoothly upward, since longer-dated debt carries more default risk and more uncertainty. But real bonds rarely sit exactly on a smooth curve: some trade a few basis points above where the curve says they "should," some below. Finding and trading those gaps is credit relative value.

Fitting the curve and reading the residual

A trader (or a curve-fitting model) draws a smooth line through an issuer's bonds using spread and duration or maturity as the axes. The vertical gap between an individual bond's actual spread and the curve's fitted spread at that maturity is the residual — the number relative-value desks actually trade on.

Worked example

An issuer's fitted credit curve implies a fair spread of 180 basis points at the 7-year point. One outstanding 7-year bond from that issuer actually trades at a spread of 210 basis points — 30 basis points cheap to the curve. A relative-value trade: buy the cheap 7-year bond, sell (or short via CDS) a curve-neutral basket of the issuer's other bonds, and wait for the 30bp gap to close as the curve reprices.

1. Identify the residual. $210 - 180 = 30$ basis points cheap.
2. Check the reason. The bond has a slightly larger issue size and thinner secondary liquidity than the issuer's benchmark bonds — a real, structural reason for some of the gap, not necessarily an error to arbitrage away in full.
3. Size the trade around the explainable portion. If a trader judges 10bp of the 30bp gap is a genuine liquidity premium and 20bp is mispricing, they size the position to profit if the spread narrows toward 190bp rather than all the way to the fitted 180bp — respecting that some of the residual is real, not noise.

What this means in practice

Curve residuals are noisy and require judgment about why a bond is off the curve before trading it: a new-issue concession, a smaller float, an approaching earnings event, or index-inclusion technicals can all produce a persistent, explainable gap that never closes. Relative-value credit desks combine curve fitting with CDS-bond basis analysis and knowledge of upcoming supply (new bond issuance from the same name, which cheapens existing bonds temporarily) to separate real mispricing from residuals that reflect something the simple curve model can't see.