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V-Lab

PSI 20 Portuguese Stock Index AGARCH Volatility Analysis

Volatility prediction for Monday, August 31st, 2026

1 Day

10.10%

decreased by 0.08%

1 Week

10.58%

increased by 0.40%

1 Month

12.18%

increased by 2.00%

Analysis last updated: Friday, August 28, 2026 at 05:04 PM UTC

Date Range:

from

to

6M ·

1Y ·

2Y ·

5Y ·

10Y ·

All

graph of PSI 20 Portuguese Stock Index AGARCH

News Impact Curve

How returns affect tomorrow's volatility

Volatility Forecast

How volatility evolves over time

Parameter Estimates

Dec 30, 1992 to Aug 28, 2026

Model 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

Tap to view equation

ParameterValuet-statistic
ω

const

Unconditional variance weight

0.0210
20.89***
α

ARCH

Response to squared shocks

0.1295
50.71***
β

GARCH

Volatility persistence

0.8559
351.94***
γ

leverage

Additional response to negative shocks

0.1974
16.49***

Persistence:

0.985

Half-life:

47 days