Skip to main content
V-Lab

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

Volatility prediction for Monday, August 24th, 2026

1 Day

11.09%

decreased by 0.19%

1 Week

11.31%

increased by 0.03%

1 Month

12.06%

increased by 0.78%

Analysis last updated: Friday, August 21, 2026 at 10:49 PM UTC

Date Range:

from

to

6M ·

1Y ·

2Y ·

5Y ·

10Y ·

All

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

News Impact Curve

How returns affect tomorrow's volatility

Volatility Forecast

How volatility evolves over time

Parameter Estimates

Oct 2, 2000 to Aug 21, 2026

Model Insight

Volatility shocks decay with a half-life of 47 trading days, meaning a shock loses half its impact after approximately 47 days. Returns follow a Student-t distribution with v = 6.84 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

1.1470
8.96***
α

ARCH

Response to squared shocks

0.0950
40.70***
β

GARCH

Volatility persistence

0.9852
567.52***
ν

DF

Student-t tail thickness

6.8430
8.49***

Persistence:

0.985

Half-life:

47 days