V-Lab
Vanguard S&P 500 Index ETF GAS-GARCH Student T Volatility Analysis
Volatility prediction for Monday, July 27th, 2026
1 Day
12.83%
decreased by 1.03%
1 Week
12.93%
decreased by 0.93%
1 Month
13.24%
decreased by 0.62%
Analysis last updated: Saturday, July 25, 2026 at 09:14 AM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Nov 8, 2012 to Jul 24, 2026Model Insight
Volatility shocks decay with a half-life of 14 trading days, meaning a shock loses half its impact after approximately 14 days. Returns follow a Student-t distribution with v = 9.10 degrees of freedom, capturing fatter tails than a normal distribution.
𝑓
GAS-GARCH-T Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.7691 | 16.70*** |
α ARCH Response to squared shocks | 0.1114 | 21.21*** |
β GARCH Volatility persistence | 0.9510 | 257.79*** |
ν DF Student-t tail thickness | 9.0950 | 3.61*** |
Persistence:
0.951
Half-life:
14 days
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