S&P Composite 1500 Index GAS-GARCH Student T Volatility Analysis
Volatility prediction for Friday, October 23rd, 2026
1 Day
12.58%
increased by 1.29%
1 Week
12.74%
increased by 1.45%
1 Month
13.31%
increased by 2.02%
Analysis last updated: Thursday, October 22, 2026 at 11:08 PM UTC
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News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Oct 31, 1994 to Oct 16, 2026Model Insight
Volatility shocks decay with a half-life of 58 trading days, meaning a shock loses half its impact after approximately 58 days. Returns follow a Student-t distribution with v = 7.58 degrees of freedom, capturing fatter tails than a normal distribution.
𝑓
GAS-GARCH-T Model
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Shock decay: Shocks decay with a 58-day half-lifev = 7.58 · fat tails
| Param | Value | t-stat |
|---|---|---|
| ωlong-run | 1.3127 | 1.81* |
| αscore | 0.0920 | 9.57*** |
| βpersistence | 0.9880 | 134.70*** |
| νDF | 7.5817 | 1.73* |
0.988
Persistence58d
Half-life𝑓
GAS-GARCH-T Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω long-run Long-run variance given a price move | 1.3127 | 1.81* |
α score Weight on the scaled score | 0.0920 | 9.57*** |
β persistence Volatility persistence | 0.9880 | 134.70*** |
ν DF Student-t tail thickness | 7.5817 | 1.73* |
Persistence:
0.988
Half-life:
58 days
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