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V-Lab

Straits Times Index STI APARCH Volatility Analysis

Volatility prediction for Thursday, August 20th, 2026

1 Day

12.46%

decreased by 0.75%

1 Week

12.76%

decreased by 0.45%

1 Month

13.81%

increased by 0.60%

Analysis last updated: Wednesday, August 19, 2026 at 10:03 AM UTC

Date Range:

from

to

6M ·

1Y ·

2Y ·

5Y ·

10Y ·

All

graph of Straits Times Index STI APARCH

News Impact Curve

How returns affect tomorrow's volatility

Volatility Forecast

How volatility evolves over time

Parameter Estimates

Jan 1, 1990 to Aug 14, 2026

Model Insight

This asset exhibits a strong leverage effect: negative returns increase next-day volatility 140% more than equivalent positive returns. The volatility power δ = 1.60 sits below 2, so large shocks influence volatility less than quadratically, a more outlier-robust response than standard GARCH.

σ

APARCH Model

Tap to view equation

ParameterValuet-statistic
ω

const

Unconditional variance weight

0.0261
27.86***
α

ARCH

Response to squared shocks

0.1263
41.75***
β

GARCH

Volatility persistence

0.8662
259.33***
γ

leverage

Additional response to negative shocks

0.2668
24.49***
δ

power

Transformation power

1.6038
30.73***

Persistence:

0.981

Half-life:

37 days