Robust Reinforcement Learning in Finance: Modeling Market Impact with Elliptic Uncertainty Sets

Fuente: arXiv
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Main Authors: Ma, Shaocong, Huang, Heng
Format: Preprint
Published: 2025
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author Ma, Shaocong
Huang, Heng
author_facet Ma, Shaocong
Huang, Heng
contents In financial applications, reinforcement learning (RL) agents are commonly trained on historical data, where their actions do not influence prices. However, during deployment, these agents trade in live markets where their own transactions can shift asset prices, a phenomenon known as market impact. This mismatch between training and deployment environments can significantly degrade performance. Traditional robust RL approaches address this model misspecification by optimizing the worst-case performance over a set of uncertainties, but typically rely on symmetric structures that fail to capture the directional nature of market impact. To address this issue, we develop a novel class of elliptic uncertainty sets. We establish both implicit and explicit closed-form solutions for the worst-case uncertainty under these sets, enabling efficient and tractable robust policy evaluation. Experiments on single-asset and multi-asset trading tasks demonstrate that our method achieves superior Sharpe ratio and remains robust under increasing trade volumes, offering a more faithful and scalable approach to RL in financial markets.
format Preprint
id arxiv_https___arxiv_org_abs_2510_19950
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Robust Reinforcement Learning in Finance: Modeling Market Impact with Elliptic Uncertainty Sets
Ma, Shaocong
Huang, Heng
Machine Learning
Artificial Intelligence
Optimization and Control
In financial applications, reinforcement learning (RL) agents are commonly trained on historical data, where their actions do not influence prices. However, during deployment, these agents trade in live markets where their own transactions can shift asset prices, a phenomenon known as market impact. This mismatch between training and deployment environments can significantly degrade performance. Traditional robust RL approaches address this model misspecification by optimizing the worst-case performance over a set of uncertainties, but typically rely on symmetric structures that fail to capture the directional nature of market impact. To address this issue, we develop a novel class of elliptic uncertainty sets. We establish both implicit and explicit closed-form solutions for the worst-case uncertainty under these sets, enabling efficient and tractable robust policy evaluation. Experiments on single-asset and multi-asset trading tasks demonstrate that our method achieves superior Sharpe ratio and remains robust under increasing trade volumes, offering a more faithful and scalable approach to RL in financial markets.
title Robust Reinforcement Learning in Finance: Modeling Market Impact with Elliptic Uncertainty Sets
topic Machine Learning
Artificial Intelligence
Optimization and Control
url https://arxiv.org/abs/2510.19950