V-Lab
State Street SPDR S&P Biotech ETF GJR-GARCH Volatility Analysis
Volatility prediction for Monday, September 21st, 2026
1 Day
27.61%
decreased by 0.37%
1 Week
27.75%
decreased by 0.23%
1 Month
28.22%
increased by 0.24%
Analysis last updated: Friday, September 18, 2026 at 11:22 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Feb 6, 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 | 0.0762 | 3.95*** |
| αARCH | 0.0161 | 1.83* |
| βGARCH | 0.9140 | 89.66*** |
| γleverage | 0.0995 | 3.96*** |
0.980
Persistence34d
Half-lifeσ
GJR-GARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0762 | 3.95*** |
α ARCH Response to squared shocks | 0.0161 | 1.83* |
β GARCH Volatility persistence | 0.9140 | 89.66*** |
γ leverage Additional response to negative shocks | 0.0995 | 3.96*** |
Persistence:
0.980
Half-life:
34 days
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