S&P GSCI Agricultural Spot Index APARCH Volatility Analysis
Volatility prediction for Monday, October 19th, 2026
1 Day
15.40%
1 Week
15.46%
1 Month
15.68%
Analysis last updated: Friday, October 16, 2026 at 11:52 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 2, 1990 to Oct 16, 2026Model Insight
With persistence 0.991, volatility shocks have a half-life of 77 trading days (~0.3 years), close to a unit root, so long-run forecasts are highly sensitive to this estimate. The volatility power δ = 1.66 sits below 2, so large shocks influence volatility less than quadratically, a more outlier-robust response than standard GARCH.
APARCH Model
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| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.0115 | 4.80*** |
| αARCH | 0.0606 | 9.40*** |
| βGARCH | 0.9366 | 158.10*** |
| γleverage | -0.0684 | -1.67* |
| δpower | 1.6624 | 8.22*** |
0.991
Persistence77d
Half-lifeAPARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0115 | 4.80*** |
α ARCH Response to squared shocks | 0.0606 | 9.40*** |
β GARCH Volatility persistence | 0.9366 | 158.10*** |
γ leverage Additional response to negative shocks | -0.0684 | -1.67* |
δ power Transformation power | 1.6624 | 8.22*** |
Persistence:
0.991
Half-life:
77 days
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