State Street SPDR S&P Metals & Mining ETF GAS-GARCH Student T Volatility Analysis
Volatility prediction for Tuesday, October 20th, 2026
1 Day
31.17%
decreased by 1.07%
1 Week
31.27%
decreased by 0.97%
1 Month
31.65%
decreased by 0.59%
Analysis last updated: Monday, October 19, 2026 at 09:58 PM UTC
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How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jun 22, 2006 to Oct 16, 2026Model Insight
With persistence 0.993, volatility shocks have a half-life of 103 trading days (~0.4 years), close to a unit root, so long-run forecasts are highly sensitive to this estimate. Returns follow a Student-t distribution with v = 9.95 degrees of freedom, capturing fatter tails than a normal distribution.
𝑓
GAS-GARCH-T Model
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High persistence: persistence 0.993, shock half-life ~103 daysv = 9.95 · fat tails
| Param | Value | t-stat |
|---|---|---|
| ωconst | 5.7004 | 1.66* |
| αARCH | 0.0557 | 7.94*** |
| βGARCH | 0.9933 | 226.36*** |
| νDF | 9.9494 | 0.83 |
0.993
Persistence103d
Half-life𝑓
GAS-GARCH-T Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 5.7004 | 1.66* |
α ARCH Response to squared shocks | 0.0557 | 7.94*** |
β GARCH Volatility persistence | 0.9933 | 226.36*** |
ν DF Student-t tail thickness | 9.9494 | 0.83 |
Persistence:
0.993
Half-life:
103 days
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