V-Lab
CBOE S&P 500 9-Day Volatility Index GAS-GARCH Student T Volatility Analysis
Volatility prediction for Tuesday, September 15th, 2026
1 Day
238.96%
increased by 4.95%
1 Week
224.95%
decreased by 9.06%
1 Month
207.15%
decreased by 26.86%
Analysis last updated: Tuesday, September 15, 2026 at 03:41 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 3, 2011 to Sep 11, 2026Model Insight
Volatility shocks decay with a half-life of 3 trading days, meaning a shock loses half its impact after approximately 3 days. Returns follow a Student-t distribution with v = 5.24 degrees of freedom, capturing fatter tails than a normal distribution.
𝑓
GAS-GARCH-T Model
Tap to view equation
Shock decay: Shocks decay with a 3-day half-lifev = 5.24 · fat tails
| Param | Value | t-stat |
|---|---|---|
| ωconst | 155.4384 | 4.89*** |
| αARCH | 0.1138 | 2.69*** |
| βGARCH | 0.7727 | 12.83*** |
| νDF | 5.2381 | 0.80 |
0.773
Persistence3d
Half-life𝑓
GAS-GARCH-T Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 155.4384 | 4.89*** |
α ARCH Response to squared shocks | 0.1138 | 2.69*** |
β GARCH Volatility persistence | 0.7727 | 12.83*** |
ν DF Student-t tail thickness | 5.2381 | 0.80 |
Persistence:
0.773
Half-life:
3 days
Other CBOE S&P 500 9-Day Volatility Index Analyses
Other GAS-GARCH Student T Analyses on Volatility Indices