Par yield curve — comparison

Both lines are par yield curves fitted to the conventional gilts each report priced on its own day: the coupon a new gilt of that maturity would need to trade at par. Neither line joins the gilts' own points — each is a fit through them — so a single gilt trading off the curve does not bend it.

The reading is the shift: at any maturity, the gap between the two lines is how much the yield at that term moved between the two dates. The short end moving more than the long end flattens the curve; the long end leading steepens it.

The comparison needs at least three priced conventional gilts in both reports; with fewer, a fit at every term is not possible and the page says so rather than drawing a line through two points.

The key-rate strip above pairs the two dates on the same basis: four round tenors from each day's fit, with the change between them.