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V-Lab

CBOE S&P 500 One-Year Volatility Index GAS-GARCH Student T Volatility Analysis

Volatility prediction for Friday, September 11th, 2026

1 Day

27.12%

increased by 0.61%

1 Week

29.04%

increased by 2.53%

1 Month

33.85%

increased by 7.34%

Analysis last updated: Friday, September 11, 2026 at 11:30 AM UTC

Date Range:

from

to

6M ·

1Y ·

2Y ·

5Y ·

10Y ·

All

graph of CBOE S&P 500 One-Year Volatility Index GAS-GARCH-T

News Impact Curve

How returns affect tomorrow's volatility

Volatility Forecast

How volatility evolves over time

Parameter Estimates

Jan 3, 2007 to Sep 4, 2026

Model Insight

Volatility shocks decay with a half-life of 12 trading days, meaning a shock loses half its impact after approximately 12 days. Returns follow a Student-t distribution with v = 4.87 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 12-day half-lifev = 4.87 · fat tails
ParamValuet-stat
ωconst6.9683
2.13**
αARCH0.1694
6.43***
βGARCH0.9442
35.82***
νDF4.8681
2.49**

0.944

Persistence

12d

Half-life
𝑓

GAS-GARCH-T Model

Tap to view equation

ParameterValuet-statistic
ω

const

Unconditional variance weight

6.9683
2.13**
α

ARCH

Response to squared shocks

0.1694
6.43***
β

GARCH

Volatility persistence

0.9442
35.82***
ν

DF

Student-t tail thickness

4.8681
2.49**

Persistence:

0.944

Half-life:

12 days