Covariance-Aware Simplex Projection for Cardinality-Constrained Portfolio Optimization

Fuente: arXiv
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Auteur principal: Iliopoulos, Nikolaos
Format: Preprint
Publié: 2025
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author Iliopoulos, Nikolaos
author_facet Iliopoulos, Nikolaos
contents Metaheuristic algorithms for cardinality-constrained portfolio optimization require repair operators to map infeasible candidates onto the feasible region. Standard Euclidean projection treats assets as independent and can ignore the covariance structure that governs portfolio risk, potentially producing less diversified portfolios. This paper introduces Covariance-Aware Simplex Projection (CASP), a two-stage repair operator that (i) selects a target number of assets using volatility-normalized scores and (ii) projects the candidate weights using a covariance-aware geometry aligned with tracking-error risk. This provides a portfolio-theoretic foundation for using a covariance-induced distance in repair operators. On S&P 500 data (2020-2024), CASP-Basic delivers materially lower portfolio variance than standard Euclidean repair without relying on return estimates, with improvements that are robust across assets and statistically significant. Ablation results indicate that volatility-normalized selection drives most of the variance reduction, while the covariance-aware projection provides an additional, consistent improvement. We further show that optional return-aware extensions can improve Sharpe ratios, and out-of-sample tests confirm that gains transfer to realized performance. CASP integrates as a drop-in replacement for Euclidean projection in metaheuristic portfolio optimizers.
format Preprint
id arxiv_https___arxiv_org_abs_2512_19986
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Covariance-Aware Simplex Projection for Cardinality-Constrained Portfolio Optimization
Iliopoulos, Nikolaos
Portfolio Management
Machine Learning
Neural and Evolutionary Computing
Computational Finance
91G10 (Primary), 90C59 (Secondary)
G.1.6; I.2.8
Metaheuristic algorithms for cardinality-constrained portfolio optimization require repair operators to map infeasible candidates onto the feasible region. Standard Euclidean projection treats assets as independent and can ignore the covariance structure that governs portfolio risk, potentially producing less diversified portfolios. This paper introduces Covariance-Aware Simplex Projection (CASP), a two-stage repair operator that (i) selects a target number of assets using volatility-normalized scores and (ii) projects the candidate weights using a covariance-aware geometry aligned with tracking-error risk. This provides a portfolio-theoretic foundation for using a covariance-induced distance in repair operators. On S&P 500 data (2020-2024), CASP-Basic delivers materially lower portfolio variance than standard Euclidean repair without relying on return estimates, with improvements that are robust across assets and statistically significant. Ablation results indicate that volatility-normalized selection drives most of the variance reduction, while the covariance-aware projection provides an additional, consistent improvement. We further show that optional return-aware extensions can improve Sharpe ratios, and out-of-sample tests confirm that gains transfer to realized performance. CASP integrates as a drop-in replacement for Euclidean projection in metaheuristic portfolio optimizers.
title Covariance-Aware Simplex Projection for Cardinality-Constrained Portfolio Optimization
topic Portfolio Management
Machine Learning
Neural and Evolutionary Computing
Computational Finance
91G10 (Primary), 90C59 (Secondary)
G.1.6; I.2.8
url https://arxiv.org/abs/2512.19986