arXiv Machine Learning

When News Gets Old: Portfolio Allocation with Reinforcement Learning and Large Language Models

The paper investigates how the age of financial news affects portfolio decisions by comparing reinforcement learning (RL) policies that incorporate timing information with large language model (LLM) approaches that either retain or filter out older news signals. Using an LLM to extract signals from SEC disclosures, the study finds that RL models can respond to timing cues in controlled tests, yet historical returns show no consistent advantage from including such information. In contrast, filtering out older news in the LLM approach yields the highest average net return, achieving 18.43% per year when news delivery is delayed by four weeks, outperforming all RL strategies that used news.

arXiv AI
Sep 28

The Price of Thought: Does Test-Time Reasoning Pay in LLM Trading?

The study investigates whether adding inference-time reasoning to large language models (LLMs) improves trading performance. Using a controlled experiment across DeepSeek, GPT, and Gemini models, the authors varied reasoning effort while keeping other variables constant and evaluated over a full year of U.S. equities under three input conditions. Results show that additional reasoning does not reliably increase net portfolio returns and can even lead to nonmonotonic performance and unstable outcomes.

By Jiayi Chen, Guiling Wang
arXiv AI
Oct 16

Plan Before You Trade: Inference-Time Optimization for RL Trading Agents

FinPILOT is a plugin inference‑time policy optimization framework that enhances pretrained reinforcement‑learning trading agents by leveraging a multi‑step price forecaster to generate imagined market trajectories. At each decision point, it optimizes the pretrained policy using the forecaster’s predicted price path before executing a trade, without altering the original training pipeline. Across five pretrained policies and multiple market settings, FinPILOT consistently improves total return and Sharpe ratio, with gains increasing as forecast accuracy improves.

By Eun Go, Rohan Deb, Arindam Banerjee
arXiv AI
Sep 10

Alpha-R1: Alpha Screening with LLM Reasoning via Reinforcement Learning

Alpha‑R1 introduces a reinforcement‑learning aligned large language model framework that performs context‑aware alpha screening by semantically gating candidate factors against a dynamic market state description. The model, trained with group relative policy optimization using realized portfolio returns as reward, selects a sparse subset of factors whose economic rationale matches current market conditions. In a 12‑month out‑of‑sample test, Alpha‑R1 achieved annualized returns of 47.87% on the S&P 500 and 40.57% on the CSI 300, with Sharpe ratios of 1.62 and 2.23, demonstrating the effectiveness of semantic factor reranking in non‑stationary markets.

By Zuoyou Jiang, Li Zhao, Rui Sun, Ruohan Sun, Zhongjian Li, Jing Li, Daxin Jiang, Zuo Bai, Cheng Hua
arXiv Machine Learning
Sep 25

A Fast and Effective Solution to the Problem of Look-ahead Bias in LLMs

The paper addresses look‑ahead bias in large language models (LLMs) used for financial prediction, which arises because LLMs are trained on long time‑series data. It proposes a low‑cost solution that adjusts the logits of a base model at inference time using two smaller, specialized models—one fine‑tuned to forget certain information and another to retain it. Experiments show that this method removes both verbatim and semantic knowledge, corrects biases, and outperforms previous approaches.

By Humzah Merchant, Bradford Levy
arXiv AI
Sep 17

EvolveTrade: Experience-Driven Policy Refinement for Self-Evolving LLM Trading Agents

EvolveTrade is a self‑evolving framework that treats the system prompt of a tool‑using LLM trading agent as a text‑parameterized policy. After each update interval, a Policy Agent revises this policy using accumulated decision traces and portfolio feedback while keeping the backbone LLM fixed, allowing the agent to refine its information‑acquisition and portfolio‑construction procedures over time. Experiments across multiple market regimes and two LLM backbones show that EvolveTrade often improves Sharpe Ratio and Cumulative Return over fixed‑policy baselines, with behavioral analyses indicating increased code‑mediated analysis and regime‑relevant computations.

By Sehee Kim, Yumin Choi, Minki Kang, Sung Ju Hwang
arXiv AI
Sep 23

Are LLMs Good Financial User Simulators? Multi-view Investor Logic Alignment (MILA)

The study examines whether large language models (LLMs) can accurately simulate individual financial users by conducting a longitudinal paper‑trading experiment with 80 participants. Using a rolling next‑day prediction protocol, the researchers compared LLM predictions to a simple recent‑activity persistence baseline across multiple behavioral fidelity levels, from trade occurrence to asset selection and portfolio outcomes. Results show that no LLM consistently outperforms the baseline, with fidelity decreasing at finer behavioral granularity, and that recent trading history largely drives activity predictions while asset selection depends more on available evidence.

By Jiajie He, Jiangyuan Hong, Xintong Chen, Dongling Ni, Wenjin Liu