V-Lab
S&P GSCI Grains Spot Index AGARCH Volatility Analysis
Volatility prediction for Monday, September 7th, 2026
1 Day
23.26%
decreased by 0.62%
1 Week
23.24%
decreased by 0.64%
1 Month
23.13%
decreased by 0.75%
Analysis last updated: Friday, September 4, 2026 at 11:31 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 2, 1990 to Sep 4, 2026Model Insight
With persistence 0.990, volatility shocks have a half-life of 70 trading days (~0.3 years), close to a unit root, so long-run forecasts are highly sensitive to this estimate.
Asymmetry: positive returns raise volatility more
σ
AGARCH Model
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High persistence: persistence 0.990, shock half-life ~70 daysAsymmetry: positive returns raise volatility more
| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.0154 | 4.31*** |
| αARCH | 0.0555 | 10.76*** |
| βGARCH | 0.9347 | 162.16*** |
| γleverage | -0.2397 | -2.98*** |
0.990
Persistence70d
Half-lifeσ
AGARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0154 | 4.31*** |
α ARCH Response to squared shocks | 0.0555 | 10.76*** |
β GARCH Volatility persistence | 0.9347 | 162.16*** |
γ leverage Additional response to negative shocks | -0.2397 | -2.98*** |
Persistence:
0.990
Half-life:
70 days
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