Business and Finance Journal
Vol 11 No 1 (2026): Business and Finance Journal

Portfolio Optimization by Mean-Variance-Kullback-Leibler Divergence measure using the AR-GJR-GARCH Filtration: Optimization by Mean-Variance-Kullback-Leibler Divergence measure

Léon Mishindo Mbucici (School of Economics, University of Johannesburg)
John W. Muteba Mwamba Mwamba (School of Economics, University of Johannesburg)
Jules Clement Mba (School of Economics, University of Johannesburg)



Article Info

Publish Date
31 Mar 2026

Abstract

The classical Markowitz Mean-Variance optimization framework remains foundational but is often criticized for its sensitivity to estimation error and assumption of normality, leading to poorly diversified and non-robust portfolios. We propose a novel hybrid framework that integrates the Kullback-Leibler divergence measure into the mean-variance objective, regularizing the solution towards an investor-defined target distribution. This paper presents an analytical approach to portfolio optimization by integrating the classical mean-variance framework with the Kullback-Leibler (KL) divergence measure. While the mean-variance method, pioneered by Markowitz, seeks to balance expected return and risk (as measured by variance), it often assumes perfect knowledge of asset return distributions. We utilize AR-GJR-GARCH models to estimate and forecast volatility on all asset returns. To address model uncertainty and distributional robustness, we investigate the KL divergence as a regularization term, penalizing deviations from a reference distribution. This fusion results in a robust optimization framework that accounts for uncertainty in the estimated parameters. We derive closed-form solutions under certain assumptions and explore the impact of the divergence parameter on the efficient frontier. The proposed method enhances stability and reliability in portfolio allocation, particularly in data-scarce or high-volatility environments. Empirical results across global markets show that our Mean-KL (M-KL) model achieves superior diversification and higher absolute returns, though with higher volatility, demonstrating a compelling trade-off for target-oriented investors.

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Journal Info

Abbrev

BFJ

Publisher

Subject

Economics, Econometrics & Finance

Description

Business and Finance Journal UNUSA (p-ISSN: 2527-4872; e-ISSN: 2477-493X) is a scientific peer-reviewed journal published by Faculty of Economics and Business, Universitas Nahdlatul Ulama Surabaya, Indonesia. Since Established in 2016, BFJ is intended Provide a medium for dissemination of original ...