Why look beyond one yield-curve spread
A single spread such as 10-year minus 3-month or 10-year minus 2-year can tell you whether one pair of maturities is inverted. TCIB instead asks how much of the core Treasury curve is inverted at the same time.
That distinction matters because the curve can become partially inverted before a familiar endpoint spread crosses below zero. In the reviewed history, the 28-pair measure identified thousands of partial-inversion observations that the two endpoint baselines did not.
How the 0-100 score is calculated
TCIB uses eight Treasury maturities with continuous history from the start of the reviewed 1990 archive: 3-month, 6-month, 1-year, 2-year, 3-year, 5-year, 7-year, and 10-year.
Those maturities create 28 ordered shorter-versus-longer pairs. A pair counts as inverted only when the shorter yield is strictly greater than the longer yield. The score is the percentage of those 28 pairs that are inverted, so 0 means none are inverted and 100 means all 28 are inverted.
Source timing and the 2021 Treasury methodology change
The calculation uses direct U.S. Treasury nominal par-yield-curve observations rather than a third-party calculation feed. Live readings update only after Treasury exposes a dated source row with all eight required maturities.
Treasury changed its yield-curve methodology on December 6, 2021. Grizzly Bulls preserves that boundary instead of pretending the full history was generated by one unchanged estimation method.
What TCIB does not tell you
TCIB describes curve shape. It is not a recession-probability model, a market-return forecast, or a standalone trading signal.
Pairs near equal yields can flip classification after a small rate move. That makes fine changes in the score more sensitive than the broad regime, so the indicator is best read as the breadth of inversion rather than as a precise probability or timing estimate.
Low example
0.0
Sep 28, 2021
Median score
57.1
Selected sample
Average score
56.0
Selected sample
High example
100.0
Mar 13, 2023
Regime frequency in this sample| Regime | Observations | Share |
|---|
| Normal Curve | 265 | 22.4% |
| Limited Inversion | 122 | 10.3% |
| Mixed Curve | 211 | 17.8% |
| Broad Inversion | 144 | 12.2% |
| Pervasive Inversion | 443 | 37.4% |
These frequencies describe the selected historical sample. They are not probabilities for future returns or market turning points.
