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

Volatility prediction for Monday, November 16th, 2026

1 Day

17.99%

decreased by 0.99%

1 Week

18.00%

decreased by 0.98%

1 Month

18.04%

decreased by 0.94%

Analysis last updated: Saturday, November 14, 2026 at 03:22 AM UTC

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Date Range:

from

11/13/2024

to

11/13/2026

6M ·

1Y ·

2Y ·

5Y ·

10Y ·

All

graph of S&P 500 Index 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 Nov 13, 2026

Model Insight

With persistence 0.991, volatility shocks have a half-life of 73 trading days (~0.3 years), close to a unit root, so long-run forecasts are highly sensitive to this estimate. Returns follow a Student-t distribution with ν = 7.01 degrees of freedom, capturing fatter tails than a normal distribution.

𝑓

GAS-GARCH-T Model

Tap to view equation

High persistence: persistence 0.991, shock half-life ~73 daysν = 7.01 · fat tails
ParamValuet-stat
ωlong-run1.3553
1.41
αscore0.0860
10.22***
βpersistence0.9906
137.11***
νDF7.0058
1.92*

0.991

Persistence

73d

Half-life
𝑓

GAS-GARCH-T Model

Tap to view equation

ParameterValuet-statistic
ω

long-run

Long-run variance given a price move

1.3553
1.41
α

score

Weight on the scaled score

0.0860
10.22***
β

persistence

Volatility persistence

0.9906
137.11***
ν

DF

Student-t tail thickness

7.0058
1.92*

Persistence:

0.991

Half-life:

73 days