V-Lab
S&P Total Market Index GJR-GARCH Volatility Analysis
Volatility prediction for Monday, September 21st, 2026
1 Day
11.15%
decreased by 0.43%
1 Week
11.59%
increased by 0.01%
1 Month
12.96%
increased by 1.38%
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
Mar 30, 2006 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 | 0.0336 | 3.74*** |
| αARCH | 0.0103 | 0.38 |
| βGARCH | 0.8638 | 45.45*** |
| γleverage | 0.1980 | 5.18*** |
0.973
Persistence25d
Half-lifeσ
GJR-GARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0336 | 3.74*** |
α ARCH Response to squared shocks | 0.0103 | 0.38 |
β GARCH Volatility persistence | 0.8638 | 45.45*** |
γ leverage Additional response to negative shocks | 0.1980 | 5.18*** |
Persistence:
0.973
Half-life:
25 days
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