V-Lab
American Express Co GJR-GARCH Volatility Analysis
Volatility prediction for Friday, September 11th, 2026
1 Day
23.46%
decreased by 0.62%
1 Week
23.76%
decreased by 0.32%
1 Month
24.90%
increased by 0.82%
Analysis last updated: Thursday, September 10, 2026 at 09:50 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 2, 1990 to Sep 4, 2026Model Insight
With persistence 0.997, volatility shocks have a half-life of 209 trading days (~0.8 years), close to a unit root, so long-run forecasts are highly sensitive to this estimate.
Leverage: volatility responds almost entirely to negative shocks
σ
GJR-GARCH Model
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High persistence: persistence 0.997, shock half-life ~209 daysLeverage: volatility responds almost entirely to negative shocks
| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.0355 | 4.28*** |
| αARCH | 0.0172 | 3.36*** |
| βGARCH | 0.9277 | 186.62*** |
| γleverage | 0.1036 | 6.66*** |
0.997
Persistence209d
Half-lifeσ
GJR-GARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0355 | 4.28*** |
α ARCH Response to squared shocks | 0.0172 | 3.36*** |
β GARCH Volatility persistence | 0.9277 | 186.62*** |
γ leverage Additional response to negative shocks | 0.1036 | 6.66*** |
Persistence:
0.997
Half-life:
209 days
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