Ishares S&P 500 EX S&P 1 ETF Spline-GARCH Volatility Analysis
High-persistence model: shocks decay very slowly, so the theoretical long-run value may not be practically meaningful
Volatility prediction for Friday, October 16th, 2026
1 Day
8.91%
unchanged at 0.00%
1 Week
8.92%
increased by 0.01%
1 Month
8.92%
increased by 0.01%
Analysis last updated: Thursday, October 15, 2026 at 10:13 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jul 9, 2025 to Oct 9, 2026Model Insight
With persistence 1.000, volatility shocks have a half-life of 7788 trading days (~30.9 years), close to a unit root, so long-run forecasts are highly sensitive to this estimate.
τ
Spline-GARCH Model
Tap to view equation
High persistence: persistence 1.000, shock half-life ~7788 days
| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.9275 | 0.28 |
| αARCH | 0.0000 | 0.00 |
| βGARCH | 0.9999 | 0.10 |
Spline Coefficients
K=1
| γ1 | -1.8922 | -0.03 |
1.000
Persistence7788d
Half-lifeτ
Spline-GARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.9275 | 0.28 |
α ARCH Response to squared shocks | 0.0000 | 0.00 |
β GARCH Volatility persistence | 0.9999 | 0.10 |
Spline Coefficients
K=1
| γ1 | -1.8922 | -0.03 |
Persistence:
1.000
Half-life:
7788 days
Other Ishares S&P 500 EX S&P 1 ETF Analyses
Other Spline-GARCH Analyses on ETFs