S&P 500 Index GJR-GARCH Volatility Analysis
Volatility prediction for Monday, October 19th, 2026
1 Day
12.94%
increased by 1.75%
1 Week
13.11%
increased by 1.92%
1 Month
13.68%
increased by 2.49%
Analysis last updated: Saturday, October 17, 2026 at 12:24 AM UTC
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News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 1, 1990 to Oct 16, 2026Model Insight
This asset exhibits a strong leverage effect: volatility responds almost entirely to negative shocks. The ARCH response to positive shocks is negligible.
σ
GJR-GARCH Model
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Leverage: volatility responds almost entirely to negative shocks
| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.0215 | 5.16*** |
| αARCH | 0.0033 | 0.34 |
| βGARCH | 0.8975 | 104.37*** |
| γleverage | 0.1601 | 7.47*** |
0.981
Persistence36d
Half-lifeσ
GJR-GARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0215 | 5.16*** |
α ARCH Response to squared shocks | 0.0033 | 0.34 |
β GARCH Volatility persistence | 0.8975 | 104.37*** |
γ leverage Additional response to negative shocks | 0.1601 | 7.47*** |
Persistence:
0.981
Half-life:
36 days
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