PSI 20 Portuguese Stock Index AGARCH Volatility Analysis
Volatility prediction for Friday, October 30th, 2026
1 Day
13.29%
decreased by 0.09%
1 Week
13.58%
increased by 0.20%
1 Month
14.59%
increased by 1.21%
Analysis last updated: Thursday, October 29, 2026 at 06:04 PM UTC
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News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Dec 30, 1992 to Oct 23, 2026Model Insight
The news-impact curve is shifted (γ = 0.20) so that negative returns raise next-day volatility more than positive returns of the same size. The gap is largest for small shocks and narrows for larger ones.
σ
AGARCH Model
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Asymmetry: negative returns raise volatility more
| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.0211 | 5.28*** |
| αARCH | 0.1289 | 12.69*** |
| βGARCH | 0.8564 | 88.43*** |
| γleverage | 0.1963 | 4.10*** |
0.985
Persistence47d
Half-lifeσ
AGARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0211 | 5.28*** |
α ARCH Response to squared shocks | 0.1289 | 12.69*** |
β GARCH Volatility persistence | 0.8564 | 88.43*** |
γ leverage Additional response to negative shocks | 0.1963 | 4.10*** |
Persistence:
0.985
Half-life:
47 days
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