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PSI 20 Portuguese Stock Index Asy. Power MEM Volatility Analysis

Volatility prediction for Tuesday, October 20th, 2026

1 Day

12.95%

increased by 0.76%

1 Week

12.56%

increased by 0.37%

1 Month

11.44%

decreased by 0.75%

Analysis last updated: Monday, October 19, 2026 at 05:13 PM UTC

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Date Range:

from

10/19/2024

to

10/19/2026

6M ·

1Y ·

2Y ·

5Y ·

10Y ·

All

graph of PSI 20 Portuguese Stock Index APMEM

News Impact Curve

How returns affect tomorrow's volatility

Volatility Forecast

How volatility evolves over time

Parameter Estimates

Jul 18, 1997 to Oct 16, 2026

Model Insight

This asset exhibits a modest leverage effect: negative returns increase next-day volatility 35% more than equivalent positive returns. The volatility power δ = 1.11 sits below 2, so large shocks influence volatility less than quadratically, a more outlier-robust response than standard GARCH.

μ

APMEM Model

Tap to view equation

Leverage: Negative returns increase volatility 35% more than positive returnsδ = 1.11 · sub-quadratic power
ParamValuet-stat
ωconst0.0277
7.88***
αARCH0.2370
19.81***
βGARCH0.7565
64.58***
γleverage0.1354
6.89***
δpower1.1096
6.55***

0.948

Persistence

13d

Half-life
μ

APMEM Model

Tap to view equation

ParameterValuet-statistic
ω

const

Unconditional variance weight

0.0277
7.88***
α

ARCH

Response to squared shocks

0.2370
19.81***
β

GARCH

Volatility persistence

0.7565
64.58***
γ

leverage

Additional response to negative shocks

0.1354
6.89***
δ

power

Transformation power

1.1096
6.55***

Persistence:

0.948

Half-life:

13 days