Vanguard S&P 500 Index ETF APARCH Volatility Analysis
Volatility prediction for Wednesday, July 15th, 2026
1 Day
12.21%
decreased by 0.34%
1 Week
12.51%
decreased by 0.04%
1 Month
13.37%
increased by 0.82%
Analysis last updated: Wednesday, July 15, 2026 at 09:11 AM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Nov 8, 2012 to Jul 10, 2026Model Insight
Volatility shocks decay with a half-life of 13 trading days, meaning a shock loses half its impact after approximately 13 days. The volatility power δ = 1.26 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 | 0.0497 | 24.36*** |
α ARCH Response to squared shocks | 0.0819 | 1.58 |
β GARCH Volatility persistence | 0.8669 | 183.17*** |
γ leverage Additional response to negative shocks | 1.0000 | 1.02 |
δ power Transformation power | 1.2581 | 29.77*** |
Persistence:
0.947
Half-life:
13 days
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