American Express Co Spline-GARCH Volatility Analysis
Volatility prediction for Friday, October 23rd, 2026
1 Day
19.64%
decreased by 0.52%
1 Week
20.07%
decreased by 0.09%
1 Month
21.49%
increased by 1.33%
Analysis last updated: Thursday, October 22, 2026 at 09:34 PM UTC
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News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 2, 1990 to Oct 16, 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 31 trading days.
τ
Spline-GARCH Model
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Time-varying baseline: volatility reverts to a slowly-shifting spline trend
| Param | Value | t-stat |
|---|---|---|
| ωconst | 1.5281 | 7.00*** |
| αARCH | 0.0826 | 10.44*** |
| βGARCH | 0.8956 | 97.96*** |
Spline Coefficients
K=6
| γ1 | 0.0595 | 3.94*** |
| γ2 | -0.1078 | -4.51*** |
| γ3 | 0.0895 | 5.41*** |
| γ4 | -0.0683 | -4.12*** |
| γ5 | 0.0594 | 2.56** |
| γ6 | -0.0784 | -2.08** |
0.978
Persistence31d
Half-lifeτ
Spline-GARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 1.5281 | 7.00*** |
α ARCH Response to squared shocks | 0.0826 | 10.44*** |
β GARCH Volatility persistence | 0.8956 | 97.96*** |
Spline Coefficients
K=6
| γ1 | 0.0595 | 3.94*** |
| γ2 | -0.1078 | -4.51*** |
| γ3 | 0.0895 | 5.41*** |
| γ4 | -0.0683 | -4.12*** |
| γ5 | 0.0594 | 2.56** |
| γ6 | -0.0784 | -2.08** |
Persistence:
0.978
Half-life:
31 days
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