V-Lab
S&P 500 Equal Weight Index (EWI) GJR-GARCH Volatility Analysis
Volatility prediction for Monday, September 21st, 2026
1 Day
12.72%
decreased by 0.12%
1 Week
12.89%
increased by 0.05%
1 Month
13.49%
increased by 0.65%
Analysis last updated: Saturday, September 19, 2026 at 12:01 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 | 0.0186 | 5.57*** |
| αARCH | 0.0173 | 2.05** |
| βGARCH | 0.8986 | 122.78*** |
| γleverage | 0.1374 | 6.77*** |
0.985
Persistence45d
Half-lifeσ
GJR-GARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0186 | 5.57*** |
α ARCH Response to squared shocks | 0.0173 | 2.05** |
β GARCH Volatility persistence | 0.8986 | 122.78*** |
γ leverage Additional response to negative shocks | 0.1374 | 6.77*** |
Persistence:
0.985
Half-life:
45 days
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