PSI 20 Portuguese Stock Index APARCH Volatility Analysis
Volatility prediction for Monday, November 2nd, 2026
1 Day
13.71%
1 Week
13.98%
1 Month
14.94%
Analysis last updated: Friday, October 30, 2026 at 06:07 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Dec 30, 1992 to Oct 30, 2026Model Insight
This asset exhibits a notable leverage effect: negative returns increase next-day volatility 91% more than equivalent positive returns. The volatility power δ = 1.22 sits below 2, so large shocks influence volatility less than quadratically, a more outlier-robust response than standard GARCH.
APARCH Model
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| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.0298 | 7.93*** |
| αARCH | 0.1297 | 13.12*** |
| βGARCH | 0.8703 | 90.78*** |
| γleverage | 0.2579 | 6.19*** |
| δpower | 1.2223 | 8.72*** |
0.977
Persistence30d
Half-lifeAPARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0298 | 7.93*** |
α ARCH Response to squared shocks | 0.1297 | 13.12*** |
β GARCH Volatility persistence | 0.8703 | 90.78*** |
γ leverage Additional response to negative shocks | 0.2579 | 6.19*** |
δ power Transformation power | 1.2223 | 8.72*** |
Persistence:
0.977
Half-life:
30 days
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