V-Lab
Proshares S&P 500 EX-Technology ETF GJR-GARCH Volatility Analysis
Volatility prediction for Tuesday, September 8th, 2026
1 Day
12.14%
increased by 0.64%
1 Week
12.44%
increased by 0.94%
1 Month
13.34%
increased by 1.84%
Analysis last updated: Saturday, September 5, 2026 at 02:26 AM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Sep 24, 2015 to Sep 4, 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 | 0.0353 | 3.86*** |
| αARCH | 0.0104 | 0.24 |
| βGARCH | 0.8509 | 24.95*** |
| γleverage | 0.2077 | 3.46*** |
0.965
Persistence20d
Half-lifeσ
GJR-GARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0353 | 3.86*** |
α ARCH Response to squared shocks | 0.0104 | 0.24 |
β GARCH Volatility persistence | 0.8509 | 24.95*** |
γ leverage Additional response to negative shocks | 0.2077 | 3.46*** |
Persistence:
0.965
Half-life:
20 days
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