4¼% Treasury Gilt 2040

What moved the price · ISIN GB00B6460505 · report 30 Oct 2026

How to read this decomposition

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Where the change in this gilt's dirty price came from, between two stored report dates. Carry is the passage of time at the gilt's own yield — the coupons received plus the pull towards par. Rolldown is the same curve at a shorter maturity: variation is the curve's own move. Unexplained is what is left — the times the traded prices disagreed with the model, which is information rather than error.

Every price behind it is Σ flow ÷ (1 + rate/2)^periods, per £100 nominal. Conventional gilts only: the fitted curve is a par curve of conventionals, and a linker's real flows have no place on it.

Return

+£1.970 gain

30 Sep 2026 → 30 Oct 2026

Start dirty price

£87.637

model £87.769

End dirty price

£89.607

model £89.568

Mark-to-market is the traded price; mark-to-model discounts the remaining flows along the fitted curve. The decomposition below is computed on the model prices.

What moved the price

Effect	Contribution	What it is
Carry	+£0.429	The passage of time at an unchanged yield: coupons earned plus the bond getting closer to redemption.
Rolldown	+£0.165	The yield change that comes from the shorter remaining maturity — rolling down the same curve.
Variation	+£1.337	The move in the curve itself between the two dates.
Unexplained	+£0.039	The residual between the traded prices and what carry, rolldown and variation account for.

The curve, then and now

Market data as of 30 Oct 2026

Both curves are the fitted par curve of that date's conventional gilts; the marked points are this gilt's own yield against its term. Start 5.67%, end 5.50%.