Level, slope and the bend.

The level is one number for where the curve is. On 26 October 1981 it was 15.66%, the high of the sample, the same day the two-year and the five-year peaked. On 30 July 2020 it was −0.04%: the two-year and the five-year were negative and the ten-year was 0.12%, so the average slipped a hair below zero. On 18 September 2026 it was 4.94%.

The regimes are mostly regimes of this level. It averaged 11.05% in the high-yield years, 5.67% through the decline, 1.30% in the low-yield years, and 3.76% in the rise. In the low-yield years the ten-year alone averaged 2.03% and the two-year 0.63%, so the level sat below the ten-year: the curve was steep, and an average of the three tenors is lower than the long one.

A positive slope is the ordinary shape: the ten-year above the two-year. A negative slope is an inversion. The range in this sample is −2.16 points on 22 January 1990, two-year 12.74% and ten-year 10.58%, to +3.05 points on 26 February 2010, two-year 1.19% and ten-year 4.24%. The average over the whole sample is +0.54 points. On 18 September 2026 the slope was +0.63.

The low-yield years, September 2008 to the end of 2021, never inverted. The ten-year was above the two-year every day, by 1.40 points on average. The other three regimes did invert, on 42% of days in the high-yield years, 38% through the decline, and 34% in the rise. The rise's widest inversion was 1.00 point on 27 June 2023.

Five years is three-eighths of the way from two years to ten, so the straight line is 0.625 times the two-year plus 0.375 times the ten-year. The bend is the five-year minus that line. Positive means the middle sits above it. Negative means the five-year is the low point of the three.

The bend is small beside the level. Its widest points are +0.96 on 21 June 1994 and −0.59 on 29 December 1989. On the June day the five-year was 8.75%, against 7.79% on the straight line from a two-year of 7.09% to a ten-year of 8.96%. The average bend was +0.02 in the high-yield years, +0.12 through the decline, and +0.10 in the low-yield years. In the rise it flipped, averaging −0.14, and the low was −0.38 on 27 December 2023, with the five-year at 3.26% between a two-year of 3.73% and a ten-year of 3.48%. On 18 September 2026 the bend was −0.01, a straight line for any practical purpose.

Inside the Yield is a different split. It takes one maturity and separates the expected path of short rates from the term premium. These three numbers are only the shape, and they use the two-year, the five-year and the ten-year, which is why the charts start in 1979. The thirty-year is left out so the sample does not have to wait until 2016.