V-Lab
Vanguard S&P 500 ETF GJR-GARCH Volatility Analysis
Volatility prediction for Tuesday, September 29th, 2026
1 Day
11.79%
increased by 1.36%
1 Week
12.24%
increased by 1.81%
1 Month
13.60%
increased by 3.17%
Analysis last updated: Monday, September 28, 2026 at 09:56 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Sep 9, 2010 to Sep 25, 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 | 0.0413 | 4.49*** |
| αARCH | 0.0155 | 0.42 |
| βGARCH | 0.8231 | 29.89*** |
| γleverage | 0.2545 | 4.36*** |
0.966
Persistence20d
Half-lifeσ
GJR-GARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0413 | 4.49*** |
α ARCH Response to squared shocks | 0.0155 | 0.42 |
β GARCH Volatility persistence | 0.8231 | 29.89*** |
γ leverage Additional response to negative shocks | 0.2545 | 4.36*** |
Persistence:
0.966
Half-life:
20 days
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