V-Lab
State Street Health Care Select Sector SPDR ETF GAS-GARCH Student T Volatility Analysis
Volatility prediction for Tuesday, August 25th, 2026
1 Day
20.51%
decreased by 1.45%
1 Week
20.42%
decreased by 1.54%
1 Month
20.11%
decreased by 1.85%
Analysis last updated: Monday, August 24, 2026 at 09:49 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Dec 22, 1998 to Aug 21, 2026Model Insight
Volatility shocks decay with a half-life of 39 trading days, meaning a shock loses half its impact after approximately 39 days. Returns follow a Student-t distribution with v = 7.53 degrees of freedom, capturing fatter tails than a normal distribution.
𝑓
GAS-GARCH-T Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 1.2651 | 7.98*** |
α ARCH Response to squared shocks | 0.0876 | 31.03*** |
β GARCH Volatility persistence | 0.9825 | 397.61*** |
ν DF Student-t tail thickness | 7.5271 | 5.43*** |
Persistence:
0.983
Half-life:
39 days
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