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V-Lab

State Street SPDR S&P 500 ETF Trust GAS-GARCH Student T Volatility Analysis

Volatility prediction for Monday, August 17th, 2026

1 Day

12.58%

decreased by 0.76%

1 Week

12.74%

decreased by 0.60%

1 Month

13.30%

decreased by 0.04%

Analysis last updated: Friday, August 14, 2026 at 10:45 PM UTC

Date Range:

from

to

6M ·

1Y ·

2Y ·

5Y ·

10Y ·

All

graph of State Street SPDR S&P 500 ETF Trust GAS-GARCH-T

News Impact Curve

How returns affect tomorrow's volatility

Volatility Forecast

How volatility evolves over time

Parameter Estimates

Jan 29, 1993 to Aug 14, 2026

Model Insight

Volatility shocks decay with a half-life of 63 trading days, meaning a shock loses half its impact after approximately 63 days. Returns follow a Student-t distribution with v = 6.79 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

1.3526
6.65***
α

ARCH

Response to squared shocks

0.0922
41.19***
β

GARCH

Volatility persistence

0.9890
555.61***
ν

DF

Student-t tail thickness

6.7879
8.87***

Persistence:

0.989

Half-life:

63 days