V-Lab
PSI 20 Portuguese Stock Index GJR-GARCH Volatility Analysis
Volatility prediction for Wednesday, September 16th, 2026
1 Day
13.20%
decreased by 0.35%
1 Week
13.47%
decreased by 0.08%
1 Month
14.42%
increased by 0.87%
Analysis last updated: Tuesday, September 15, 2026 at 06:43 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Dec 30, 1992 to Sep 11, 2026Model Insight
This asset exhibits a strong leverage effect: negative returns increase next-day volatility 100% more than equivalent positive returns.
σ
GJR-GARCH Model
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Leverage: Negative returns increase volatility 100% more than positive returns
| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.0241 | 6.76*** |
| αARCH | 0.0859 | 6.84*** |
| βGARCH | 0.8572 | 94.81*** |
| γleverage | 0.0863 | 2.80*** |
0.986
Persistence50d
Half-lifeσ
GJR-GARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0241 | 6.76*** |
α ARCH Response to squared shocks | 0.0859 | 6.84*** |
β GARCH Volatility persistence | 0.8572 | 94.81*** |
γ leverage Additional response to negative shocks | 0.0863 | 2.80*** |
Persistence:
0.986
Half-life:
50 days
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