V-Lab
S&P 100 Index APARCH Volatility Analysis
Volatility prediction for Tuesday, September 8th, 2026
1 Day
11.93%
increased by 0.69%
1 Week
12.25%
increased by 1.01%
1 Month
13.37%
increased by 2.13%
Analysis last updated: Friday, September 4, 2026 at 11:30 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 1, 1990 to Sep 4, 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 = 1.12 sits below 2, so large shocks influence volatility less than quadratically, a more outlier-robust response than standard GARCH.
σ
APARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0279 | 7.96*** |
α ARCH Response to squared shocks | 0.0831 | 7.60*** |
β GARCH Volatility persistence | 0.9067 | 95.63*** |
γ leverage Additional response to negative shocks | 0.8281 | 4.82*** |
δ power Transformation power | 1.1163 | 10.81*** |
Persistence:
0.977
Half-life:
30 days
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