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V-Lab

S&P Total Market Index Zero Slope Spline-GARCH Volatility Analysis

Volatility prediction for Wednesday, August 26th, 2026

1 Day

11.99%

decreased by 0.38%

1 Week

12.61%

increased by 0.24%

1 Month

14.42%

increased by 2.05%

Analysis last updated: Tuesday, August 25, 2026 at 11:06 PM UTC

Date Range:

from

to

6M ·

1Y ·

2Y ·

5Y ·

10Y ·

All

graph of S&P Total Market Index S0GARCH

News Impact Curve

How returns affect tomorrow's volatility

Volatility Forecast

How volatility evolves over time

Parameter Estimates

Mar 30, 2006 to Aug 21, 2026

Model 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 20 trading days.

τ

Zero Slope Spline-GARCH Model

Tap to view equation

ParameterValuet-statistic
ω

const

Unconditional variance weight

0.8905
5.83***
α

ARCH

Response to squared shocks

0.1305
8.83***
β

GARCH

Volatility persistence

0.8350
49.39***
γi Spline Coefficients
K=3
γ1-0.0275
-2.31**
γ20.0500
2.79***
γ3-0.0312
-3.12***

Persistence:

0.966

Half-life:

20 days