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V-Lab

S&P GSCI Agricultural Spot Index GAS-GARCH Student T Volatility Analysis

Volatility prediction for Tuesday, July 21st, 2026

1 Day

20.54%

decreased by 0.62%

1 Week

20.48%

decreased by 0.68%

1 Month

20.26%

decreased by 0.90%

Analysis last updated: Monday, July 20, 2026 at 11:08 PM UTC

Date Range:

from

to

6M ·

1Y ·

2Y ·

5Y ·

10Y ·

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graph of S&P GSCI Agricultural Spot Index GAS-GARCH-T

News Impact Curve

How returns affect tomorrow's volatility

Volatility Forecast

How volatility evolves over time

Parameter Estimates

Jan 2, 1990 to Jul 17, 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 v = 10.14 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

1.1743
11.19***
α

ARCH

Response to squared shocks

0.0518
34.81***
β

GARCH

Volatility persistence

0.9905
1,076.65***
ν

DF

Student-t tail thickness

10.1354
3.95***

Persistence:

0.991

Half-life:

73 days