V-Lab
S&P GSCI Grains Spot Index GARCH Volatility Analysis
Volatility prediction for Monday, September 21st, 2026
1 Day
20.03%
decreased by 0.12%
1 Week
20.07%
decreased by 0.08%
1 Month
20.23%
increased by 0.08%
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
Jan 2, 1990 to Sep 18, 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.
σ
GARCH Model
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High persistence: persistence 0.990, shock half-life ~70 days
| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.0189 | 5.37*** |
| αARCH | 0.0583 | 10.73*** |
| βGARCH | 0.9319 | 153.75*** |
0.990
Persistence70d
Half-lifeσ
GARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0189 | 5.37*** |
α ARCH Response to squared shocks | 0.0583 | 10.73*** |
β GARCH Volatility persistence | 0.9319 | 153.75*** |
Persistence:
0.990
Half-life:
70 days
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