S&P GSCI Spot Index APARCH Volatility Analysis
Volatility prediction for Monday, October 19th, 2026
1 Day
16.13%
1 Week
16.26%
1 Month
16.75%
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 0.994, volatility shocks have a half-life of 122 trading days (~0.5 years), close to a unit root, so long-run forecasts are highly sensitive to this estimate. The volatility power δ = 1.76 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 | 0.0132 | 5.28*** |
| αARCH | 0.0735 | 8.73*** |
| βGARCH | 0.9265 | 114.19*** |
| γleverage | 0.0305 | 0.57 |
| δpower | 1.7579 | 10.16*** |
0.994
Persistence122d
Half-lifeAPARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0132 | 5.28*** |
α ARCH Response to squared shocks | 0.0735 | 8.73*** |
β GARCH Volatility persistence | 0.9265 | 114.19*** |
γ leverage Additional response to negative shocks | 0.0305 | 0.57 |
δ power Transformation power | 1.7579 | 10.16*** |
Persistence:
0.994
Half-life:
122 days
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