V-Lab
American Express Co Zero Slope Spline-GARCH Volatility Analysis
Volatility prediction for Wednesday, September 16th, 2026
1 Day
23.47%
decreased by 0.08%
1 Week
24.31%
increased by 0.76%
1 Month
27.05%
increased by 3.50%
Analysis last updated: Tuesday, September 15, 2026 at 09:20 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 2, 1990 to Sep 11, 2026Model Insight
This model fits a time-varying baseline (a spline), so volatility mean-reverts toward a slowly-shifting long-run level rather than a constant. Short-run deviations decay with a half-life of 34 trading days.
τ
Zero Slope Spline-GARCH Model
Tap to view equation
Time-varying baseline: volatility reverts to a slowly-shifting spline trend
| Param | Value | t-stat |
|---|---|---|
| ωconst | 1.5178 | 6.79*** |
| αARCH | 0.0825 | 10.46*** |
| βGARCH | 0.8971 | 101.20*** |
Spline Coefficients
K=6
| γ1 | 0.0565 | 3.63*** |
| γ2 | -0.1027 | -4.15*** |
| γ3 | 0.0847 | 4.94*** |
| γ4 | -0.0603 | -3.65*** |
| γ5 | 0.0420 | 2.19** |
| γ6 | -0.0318 | -2.14** |
0.980
Persistence34d
Half-lifeτ
Zero Slope Spline-GARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 1.5178 | 6.79*** |
α ARCH Response to squared shocks | 0.0825 | 10.46*** |
β GARCH Volatility persistence | 0.8971 | 101.20*** |
Spline Coefficients
K=6
| γ1 | 0.0565 | 3.63*** |
| γ2 | -0.1027 | -4.15*** |
| γ3 | 0.0847 | 4.94*** |
| γ4 | -0.0603 | -3.65*** |
| γ5 | 0.0420 | 2.19** |
| γ6 | -0.0318 | -2.14** |
Persistence:
0.980
Half-life:
34 days
Other American Express Co Analyses
Other Zero Slope Spline-GARCH Analyses on Equities