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

Volatility prediction for Friday, August 21st, 2026

1 Day

24.29%

increased by 0.32%

1 Week

26.73%

increased by 2.76%

1 Month

32.60%

increased by 8.63%

Analysis last updated: Friday, August 21, 2026 at 11:32 AM UTC

Date Range:

from

to

6M ·

1Y ·

2Y ·

5Y ·

10Y ·

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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 Aug 14, 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

ParameterValuet-statistic
ω

const

Unconditional variance weight

6.9821
8.54***
α

ARCH

Response to squared shocks

0.1700
25.63***
β

GARCH

Volatility persistence

0.9437
142.43***
ν

DF

Student-t tail thickness

4.8691
9.96***

Persistence:

0.944

Half-life:

12 days