V-Lab
American Express Co Zero Slope Spline-GARCH Volatility Analysis
Volatility prediction for Monday, July 27th, 2026
1 Day
33.77%
increased by 5.59%
1 Week
33.95%
increased by 5.77%
1 Month
34.53%
increased by 6.35%
Analysis last updated: Friday, July 24, 2026 at 10:22 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 2, 1990 to Jul 24, 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 27 trading days.
τ
Zero Slope Spline-GARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 1.3459 | 6.71*** |
α ARCH Response to squared shocks | 0.0812 | 10.23*** |
β GARCH Volatility persistence | 0.8933 | 87.23*** |
Spline Coefficients
K=8
| γ1 | 0.0268 | 0.91 |
| γ2 | 0.0008 | 0.02 |
| γ3 | -0.1117 | -2.69*** |
| γ4 | 0.1855 | 4.69*** |
| γ5 | -0.1739 | -3.80*** |
| γ6 | 0.1149 | 2.00** |
| γ7 | -0.0459 | -0.96 |
| γ8 | -0.0064 | -0.25 |
Persistence:
0.974
Half-life:
27 days
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