V-Lab
State Street SPDR Portfolio Aggregate Bond ETF GAS-GARCH Student T Volatility Analysis
Volatility prediction for Friday, September 4th, 2026
1 Day
3.91%
decreased by 0.18%
1 Week
3.93%
decreased by 0.16%
1 Month
4.01%
decreased by 0.08%
Analysis last updated: Thursday, September 3, 2026 at 09:49 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
May 30, 2007 to Aug 28, 2026Model Insight
With persistence 0.993, volatility shocks have a half-life of 97 trading days (~0.4 years), close to a unit root, so long-run forecasts are highly sensitive to this estimate. Returns follow a Student-t distribution with v = 10.15 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 | 0.1071 | 2.36** |
α ARCH Response to squared shocks | 0.0794 | 8.85*** |
β GARCH Volatility persistence | 0.9929 | 313.32*** |
ν DF Student-t tail thickness | 10.1456 | 1.42 |
Persistence:
0.993
Half-life:
97 days
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