V-Lab
S&P 1000 Index APARCH Volatility Analysis
Volatility prediction for Monday, September 14th, 2026
1 Day
17.60%
1 Week
17.74%
1 Month
18.24%
Analysis last updated: Saturday, September 12, 2026 at 12:53 AM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Dec 29, 1994 to Sep 11, 2026Model Insight
This asset exhibits a strong leverage effect: volatility responds almost entirely to negative shocks. The ARCH response to positive shocks is negligible. The volatility power δ = 1.00 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 | 0.0284 | 8.90*** |
| αARCH | 0.0783 | 10.00*** |
| βGARCH | 0.9162 | 117.81*** |
| γleverage | 0.8408 | 8.97*** |
| δpower | 0.9975 | 10.30*** |
0.979
Persistence32d
Half-lifeAPARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0284 | 8.90*** |
α ARCH Response to squared shocks | 0.0783 | 10.00*** |
β GARCH Volatility persistence | 0.9162 | 117.81*** |
γ leverage Additional response to negative shocks | 0.8408 | 8.97*** |
δ power Transformation power | 0.9975 | 10.30*** |
Persistence:
0.979
Half-life:
32 days
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