V-Lab
S&P 500 Growth Index GJR-GARCH Volatility Analysis
Volatility prediction for Tuesday, September 22nd, 2026
1 Day
12.24%
decreased by 0.05%
1 Week
12.50%
increased by 0.21%
1 Month
13.39%
increased by 1.10%
Analysis last updated: Monday, September 21, 2026 at 11:01 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Oct 29, 1992 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 | 0.0212 | 5.07*** |
| αARCH | 0.0070 | 0.56 |
| βGARCH | 0.9010 | 95.46*** |
| γleverage | 0.1556 | 7.32*** |
0.986
Persistence48d
Half-lifeσ
GJR-GARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0212 | 5.07*** |
α ARCH Response to squared shocks | 0.0070 | 0.56 |
β GARCH Volatility persistence | 0.9010 | 95.46*** |
γ leverage Additional response to negative shocks | 0.1556 | 7.32*** |
Persistence:
0.986
Half-life:
48 days
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