V-Lab
S&P GSCI Grains Spot Index GAS-GARCH Student T Volatility Analysis
Volatility prediction for Monday, September 21st, 2026
1 Day
19.90%
unchanged at 0.00%
1 Week
19.92%
increased by 0.02%
1 Month
19.99%
increased by 0.09%
Analysis last updated: Saturday, September 19, 2026 at 12:03 AM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 2, 1990 to Sep 18, 2026Model Insight
Volatility shocks decay with a half-life of 62 trading days, meaning a shock loses half its impact after approximately 62 days. Returns follow a Student-t distribution with v = 9.70 degrees of freedom, capturing fatter tails than a normal distribution.
𝑓
GAS-GARCH-T Model
Tap to view equation
Shock decay: Shocks decay with a 62-day half-lifev = 9.70 · fat tails
| Param | Value | t-stat |
|---|---|---|
| ωconst | 1.7083 | 3.29*** |
| αARCH | 0.0531 | 8.71*** |
| βGARCH | 0.9889 | 308.64*** |
| νDF | 9.6991 | 1.08 |
0.989
Persistence62d
Half-life𝑓
GAS-GARCH-T Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 1.7083 | 3.29*** |
α ARCH Response to squared shocks | 0.0531 | 8.71*** |
β GARCH Volatility persistence | 0.9889 | 308.64*** |
ν DF Student-t tail thickness | 9.6991 | 1.08 |
Persistence:
0.989
Half-life:
62 days
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