FinEvo: Financial Language Agents Shape the Markets That Evaluate Them

Mingxi Zou, Jiaxiang Chen, Langzhang Liang, Zhuo Wang, Aotian Luo, Chi Zhang, Danny Dongning Sun, Zenglin Xu


Abstract
Financial language agents are commonly evaluated through static prediction tasks or isolated historical backtests, where an agent’s decisions cannot affect subsequent prices or the behavior of competing strategies. This overlooks a defining property of real markets: interpretations of financial news influence order flow, price formation, and the competitive environment faced by other participants. We introduce FINEVO, a closed-loop evaluation framework that integrates time-stamped financial news, heterogeneous trading agents, a continuous double-auction market, and population-level capital reallocation. FINEVO evaluates language-based agents alongside technical, forecasting, reinforcement-learning, and informed strategies, reporting not only returns but also market concentration, strategic reorganization, regime-dependent standing, and recovery from shocks. Across 128-run suites of controlled market shocks and historical-news-conditioned episodes, we find that language-agent performance is strongly contingent on the surrounding market regime and agent population. Endogenous price formation also causes identical information schedules to produce different outcomes under different competitive compositions. Mechanism ablations further show that innovation is critical for maintaining contestability: removing it increases mean HHI from 0.189 to 0.477 and mean Top-1 capital share from 0.344 to 0.531. These results suggest that financial language agents should be evaluated not only by how accurately they interpret information, but also by how their decisions reshape the markets in which they operate.
Anthology ID:
2026.finnlp-1.5
Volume:
Proceedings of the 11th Workshop on Financial Technology and Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Jimin Huang, Yongjae Lee, Sophia Ananiadou, Hsin-Hsi Chen, Hiroya Takamura, Chung-Chi Chen
Venues:
FinNLP | WS
SIG:
SIGFinTech
Publisher:
Association for Computational Linguistics
Note:
Pages:
31–52
Language:
URL:
https://aclanthology.org/2026.finnlp-1.5/
DOI:
Bibkey:
Cite (ACL):
Mingxi Zou, Jiaxiang Chen, Langzhang Liang, Zhuo Wang, Aotian Luo, Chi Zhang, Danny Dongning Sun, and Zenglin Xu. 2026. FinEvo: Financial Language Agents Shape the Markets That Evaluate Them. In Proceedings of the 11th Workshop on Financial Technology and Natural Language Processing, pages 31–52, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
FinEvo: Financial Language Agents Shape the Markets That Evaluate Them (Zou et al., FinNLP 2026)
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PDF:
https://aclanthology.org/2026.finnlp-1.5.pdf