DRNash: Efficient and Robust Multi-Task Learning for Financial Sentiment Analysis

Hongcheng Ding, Xuanhuang Liu, Deshinta Arrova Dewi, Shamsul Nahar Abdullah, Qingyu Liu, Xuanze Zhao


Abstract
Fine-tuning large language models (LLMs) for sentiment polarity regression often suffers from severe data distribution imbalance. Financial texts typically concentrate in the neutral range, leaving extreme sentiments underrepresented, yet traditional techniques offer limited remedy since such extremes are inherently rare. We introduce an auxiliary classification task to provide complementary supervision, but this multi-task formulation faces two challenges: (1) sentiment group construction for the classification task, and (2) gradient conflicts between tasks that fixed weights cannot resolve. These challenges are coupled: improper group boundaries yield biased gradients, which amplify task conflicts. We propose the DRNash framework as a unified solution to jointly address both challenges and the underlying data distribution imbalance, including Distributionally Robust Optimization (DRO) and Nash Task Coordinator (NTC). DRO partitions the sentiment space into quantile-based groups and performs worst-case aggregation over group losses, automatically assigning higher weights to underperforming sentiment regions. NTC formulates task weighting as a Nash bargaining game, deriving closed-form weights that achieve scale-invariant balancing. Experiments demonstrate that DRNash achieves average improvements of 14.1% in MSE and 1.92% in accuracy (ACC) across multiple financial datasets, with cross-domain experiments confirming generalizability beyond financial texts.
Anthology ID:
2026.findings-emnlp.137
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
2795–2846
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URL:
https://aclanthology.org/2026.findings-emnlp.137/
DOI:
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Cite (ACL):
Hongcheng Ding, Xuanhuang Liu, Deshinta Arrova Dewi, Shamsul Nahar Abdullah, Qingyu Liu, and Xuanze Zhao. 2026. DRNash: Efficient and Robust Multi-Task Learning for Financial Sentiment Analysis. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 2795–2846, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
DRNash: Efficient and Robust Multi-Task Learning for Financial Sentiment Analysis (Ding et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.137.pdf