Even for a rolling investor (whose returns are also driven by mark-to-market spread moves), initial spreads explain nearly half of 5yr forward returns.
Why it is true (even for a rolling/MTM investor) Credit excess returns for a rolling investor (constant-maturity index style, or someone continuously reinvesting as bonds mature/roll) can be decomposed roughly as:
Excess return≈ Carry (spread income) - Duration x ΔSpread+other (defaults, convexity, etc.)
- The carry term is directly tied to the level of spreads.
- The mark-to-market term comes from spread changes. Spreads are mean-reverting over multi-year horizons, so the starting level strongly influences both the path of subsequent spreads and the expected direction/magnitude of MTM moves.
The starting points matter:
- Starting from wide spreads → high ongoing carry + higher probability of subsequent tightening (positive MTM contribution).
- Starting from tight spreads → low carry + higher probability of subsequent widening (negative MTM contributi

