arXiv Machine Learning By Bolin Song (Cornell University), Surui Xiang (United Nations)

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

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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.

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