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V-Lab

S&P 500 Equal Weight Index (EWI) GAS-GARCH Student T Volatility Analysis

Volatility prediction for Monday, November 2nd, 2026

1 Day

12.42%

increased by 0.32%

1 Week

12.55%

increased by 0.45%

1 Month

13.02%

increased by 0.92%

Analysis last updated: Friday, October 30, 2026 at 11:05 PM UTC

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Date Range:

from

10/30/2024

to

10/30/2026

6M ·

1Y ·

2Y ·

5Y ·

10Y ·

All

graph of S&P 500 Equal Weight Index (EWI) GAS-GARCH-T

News Impact Curve

How returns affect tomorrow's volatility

Volatility Forecast

How volatility evolves over time

Parameter Estimates

Jan 1, 1990 to Oct 30, 2026

Model Insight

Volatility shocks decay with a half-life of 69 trading days, meaning a shock loses half its impact after approximately 69 days. Returns follow a Student-t distribution with v = 8.58 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 69-day half-lifev = 8.58 · fat tails
ParamValuet-stat
ωlong-run1.2540
1.88*
αscore0.0846
10.11***
βpersistence0.9900
169.02***
νDF8.5830
1.47

0.990

Persistence

69d

Half-life
𝑓

GAS-GARCH-T Model

Tap to view equation

ParameterValuet-statistic
ω

long-run

Long-run variance given a price move

1.2540
1.88*
α

score

Weight on the scaled score

0.0846
10.11***
β

persistence

Volatility persistence

0.9900
169.02***
ν

DF

Student-t tail thickness

8.5830
1.47

Persistence:

0.990

Half-life:

69 days