PSI 20 Portuguese Stock Index MEM Volatility Analysis
Volatility prediction for Monday, July 20th, 2026
1 Day
12.47%
decreased by 0.64%
1 Week
12.86%
decreased by 0.25%
1 Month
14.25%
increased by 1.14%
Analysis last updated: Friday, July 17, 2026 at 05:05 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jul 18, 1997 to Jul 17, 2026Model Insight
With persistence 0.994, volatility shocks have a half-life of 109 trading days (~0.4 years), close to a unit root, so long-run forecasts are highly sensitive to this estimate.
μ
MEM Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0235 | 8.70*** |
α ARCH Response to squared shocks | 0.2575 | 53.29*** |
β GARCH Volatility persistence | 0.7362 | 253.15*** |
Persistence:
0.994
Half-life:
109 days
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