IBEX 35 Index Zero Slope Spline-GARCH Volatility Analysis
Volatility prediction for Friday, October 23rd, 2026
1 Day
18.73%
increased by 2.97%
1 Week
18.62%
increased by 2.86%
1 Month
18.29%
increased by 2.53%
Analysis last updated: Thursday, October 22, 2026 at 04:15 PM UTC
Press Delete or Backspace to remove this series.
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 2, 1990 to Oct 16, 2026Model Insight
This model fits a time-varying baseline (a spline), so volatility mean-reverts toward a slowly-shifting long-run level rather than a constant. Short-run deviations decay with a half-life of 17 trading days.
τ
Zero Slope Spline-GARCH Model
Tap to view equation
Time-varying baseline: volatility reverts to a slowly-shifting spline trend
| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.9017 | 5.52*** |
| αARCH | 0.1102 | 9.08*** |
| βGARCH | 0.8496 | 73.50*** |
Spline Coefficients
K=8
| γ1 | -0.0301 | -0.85 |
| γ2 | 0.0674 | 1.12 |
| γ3 | -0.0989 | -2.29** |
| γ4 | 0.1442 | 4.71*** |
| γ5 | -0.1532 | -6.12*** |
| γ6 | 0.0965 | 3.53*** |
| γ7 | -0.0281 | -1.02 |
| γ8 | 0.0047 | 0.26 |
0.960
Persistence17d
Half-lifeτ
Zero Slope Spline-GARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.9017 | 5.52*** |
α ARCH Response to squared shocks | 0.1102 | 9.08*** |
β GARCH Volatility persistence | 0.8496 | 73.50*** |
Spline Coefficients
K=8
| γ1 | -0.0301 | -0.85 |
| γ2 | 0.0674 | 1.12 |
| γ3 | -0.0989 | -2.29** |
| γ4 | 0.1442 | 4.71*** |
| γ5 | -0.1532 | -6.12*** |
| γ6 | 0.0965 | 3.53*** |
| γ7 | -0.0281 | -1.02 |
| γ8 | 0.0047 | 0.26 |
Persistence:
0.960
Half-life:
17 days
Other IBEX 35 Index Analyses
Other Zero Slope Spline-GARCH Analyses on Equity Indices