V-Lab
S&P 500 Equal Weight Index (EWI) GJR-GARCH Volatility Analysis
Volatility prediction for Monday, September 14th, 2026
1 Day
13.33%
decreased by 0.43%
1 Week
13.47%
decreased by 0.29%
1 Month
13.99%
increased by 0.23%
Analysis last updated: Saturday, September 12, 2026 at 12:53 AM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 1, 1990 to Sep 11, 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 | 0.0187 | 5.57*** |
| αARCH | 0.0173 | 2.05** |
| βGARCH | 0.8985 | 122.66*** |
| γleverage | 0.1377 | 6.78*** |
0.985
Persistence45d
Half-lifeσ
GJR-GARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0187 | 5.57*** |
α ARCH Response to squared shocks | 0.0173 | 2.05** |
β GARCH Volatility persistence | 0.8985 | 122.66*** |
γ leverage Additional response to negative shocks | 0.1377 | 6.78*** |
Persistence:
0.985
Half-life:
45 days
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