V-Lab
S&P 500 Index GJR-GARCH Volatility Analysis
Volatility prediction for Monday, September 21st, 2026
1 Day
10.61%
decreased by 0.32%
1 Week
10.91%
decreased by 0.02%
1 Month
11.90%
increased by 0.97%
Analysis last updated: Saturday, September 19, 2026 at 03:32 AM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 1, 1990 to Sep 18, 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 | 0.0216 | 5.16*** |
| αARCH | 0.0035 | 0.36 |
| βGARCH | 0.8972 | 104.23*** |
| γleverage | 0.1602 | 7.44*** |
0.981
Persistence36d
Half-lifeσ
GJR-GARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0216 | 5.16*** |
α ARCH Response to squared shocks | 0.0035 | 0.36 |
β GARCH Volatility persistence | 0.8972 | 104.23*** |
γ leverage Additional response to negative shocks | 0.1602 | 7.44*** |
Persistence:
0.981
Half-life:
36 days
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