V-Lab
Wal-Mart Stores Inc GAS-GARCH Student T Volatility Analysis
Volatility prediction for Monday, September 14th, 2026
1 Day
23.02%
increased by 0.33%
1 Week
23.06%
increased by 0.37%
1 Month
23.21%
increased by 0.52%
Analysis last updated: Friday, September 11, 2026 at 11:40 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 2, 1990 to Sep 11, 2026Model Insight
With persistence 0.995, volatility shocks have a half-life of 144 trading days (~0.6 years), close to a unit root, so long-run forecasts are highly sensitive to this estimate. Returns follow a Student-t distribution with v = 5.18 degrees of freedom, capturing fatter tails than a normal distribution.
𝑓
GAS-GARCH-T Model
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High persistence: persistence 0.995, shock half-life ~144 daysv = 5.18 · fat tails
| Param | Value | t-stat |
|---|---|---|
| ωconst | 2.8446 | 1.09 |
| αARCH | 0.0537 | 12.90*** |
| βGARCH | 0.9952 | 227.63*** |
| νDF | 5.1837 | 3.45*** |
0.995
Persistence144d
Half-life𝑓
GAS-GARCH-T Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 2.8446 | 1.09 |
α ARCH Response to squared shocks | 0.0537 | 12.90*** |
β GARCH Volatility persistence | 0.9952 | 227.63*** |
ν DF Student-t tail thickness | 5.1837 | 3.45*** |
Persistence:
0.995
Half-life:
144 days
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