V-Lab
S&P SmallCap 600 Index APARCH Volatility Analysis
Volatility prediction for Monday, September 14th, 2026
1 Day
17.13%
1 Week
17.30%
1 Month
17.87%
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
Jan 1, 1990 to Sep 11, 2026Model Insight
This asset exhibits a strong leverage effect: negative returns increase next-day volatility 299% more than equivalent positive returns. The volatility power δ = 0.94 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 | 0.0270 | 8.69*** |
| αARCH | 0.0851 | 11.85*** |
| βGARCH | 0.9125 | 126.10*** |
| γleverage | 0.6265 | 10.59*** |
| δpower | 0.9413 | 9.01*** |
0.979
Persistence33d
Half-lifeAPARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0270 | 8.69*** |
α ARCH Response to squared shocks | 0.0851 | 11.85*** |
β GARCH Volatility persistence | 0.9125 | 126.10*** |
γ leverage Additional response to negative shocks | 0.6265 | 10.59*** |
δ power Transformation power | 0.9413 | 9.01*** |
Persistence:
0.979
Half-life:
33 days
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