V-Lab
Vanguard S&P 500 ETF GAS-GARCH Student T Volatility Analysis
Volatility prediction for Wednesday, August 12th, 2026
1 Day
13.25%
decreased by 1.04%
1 Week
13.44%
decreased by 0.85%
1 Month
14.09%
decreased by 0.20%
Analysis last updated: Tuesday, August 11, 2026 at 10:16 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Sep 9, 2010 to Aug 7, 2026Model Insight
Volatility shocks decay with a half-life of 27 trading days, meaning a shock loses half its impact after approximately 27 days. Returns follow a Student-t distribution with v = 6.69 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 | 1.1207 | 7.14*** |
α ARCH Response to squared shocks | 0.1291 | 27.47*** |
β GARCH Volatility persistence | 0.9748 | 246.29*** |
ν DF Student-t tail thickness | 6.6868 | 6.50*** |
Persistence:
0.975
Half-life:
27 days
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