V-Lab
Vanguard S&P 500 Index ETF AGARCH Volatility Analysis
Volatility prediction for Monday, August 10th, 2026
1 Day
17.84%
decreased by 1.34%
1 Week
17.53%
decreased by 1.65%
1 Month
16.68%
decreased by 2.50%
Analysis last updated: Saturday, August 8, 2026 at 09:18 AM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Nov 8, 2012 to Aug 7, 2026Model Insight
The news-impact curve is shifted (γ = 0.64) so that negative returns raise next-day volatility more than positive returns of the same size. The gap is largest for small shocks and narrows for larger ones.
σ
AGARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0135 | 4.05*** |
α ARCH Response to squared shocks | 0.1036 | 27.50*** |
β GARCH Volatility persistence | 0.8340 | 157.77*** |
γ leverage Additional response to negative shocks | 0.6396 | 22.82*** |
Persistence:
0.938
Half-life:
11 days
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