V-Lab
S&P Composite 1500 Index GAS-GARCH Student T Volatility Analysis
Volatility prediction for Monday, September 21st, 2026
1 Day
12.90%
decreased by 0.81%
1 Week
13.05%
decreased by 0.66%
1 Month
13.59%
decreased by 0.12%
Analysis last updated: Saturday, September 19, 2026 at 12:02 AM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Oct 31, 1994 to Sep 18, 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 = 7.56 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 = 7.56 · fat tails
| Param | Value | t-stat |
|---|---|---|
| ωconst | 1.3184 | 1.80* |
| αARCH | 0.0921 | 9.56*** |
| βGARCH | 0.9881 | 134.56*** |
| νDF | 7.5619 | 1.74* |
0.988
Persistence58d
Half-life𝑓
GAS-GARCH-T Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 1.3184 | 1.80* |
α ARCH Response to squared shocks | 0.0921 | 9.56*** |
β GARCH Volatility persistence | 0.9881 | 134.56*** |
ν DF Student-t tail thickness | 7.5619 | 1.74* |
Persistence:
0.988
Half-life:
58 days
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