V-Lab
State Street SPDR Portfolio Aggregate Bond ETF APARCH Volatility Analysis
Volatility prediction for Friday, September 4th, 2026
1 Day
3.81%
decreased by 0.14%
1 Week
3.84%
decreased by 0.11%
1 Month
3.95%
increased by 0.00%
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 0.992, volatility shocks have a half-life of 87 trading days (~0.3 years), close to a unit root, so long-run forecasts are highly sensitive to this estimate.
σ
APARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0010 | 2.29** |
α ARCH Response to squared shocks | 0.0847 | 8.06*** |
β GARCH Volatility persistence | 0.9088 | 63.22*** |
γ leverage Additional response to negative shocks | 0.1162 | 1.80* |
δ power Transformation power | 1.9162 | 6.01*** |
Persistence:
0.992
Half-life:
87 days
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