V-Lab
PSI 20 Portuguese Stock Index GAS-GARCH Student T Volatility Analysis
Volatility prediction for Friday, July 24th, 2026
1 Day
13.02%
decreased by 0.77%
1 Week
13.16%
decreased by 0.63%
1 Month
13.70%
decreased by 0.09%
Analysis last updated: Friday, July 24, 2026 at 12:04 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Dec 30, 1992 to Jul 17, 2026Model Insight
With persistence 0.994, volatility shocks have a half-life of 124 trading days (~0.5 years), close to a unit root, so long-run forecasts are highly sensitive to this estimate. Returns follow a Student-t distribution with v = 6.69 degrees of freedom, capturing fatter tails than a normal distribution.
𝑓
GAS-GARCH-T Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 2.0082 | 5.46*** |
α ARCH Response to squared shocks | 0.0961 | 59.53*** |
β GARCH Volatility persistence | 0.9944 | 985.54*** |
ν DF Student-t tail thickness | 6.6887 | 12.69*** |
Persistence:
0.994
Half-life:
124 days
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