Enhancing large language models for bitcoin time series forecasting

Citation

Chaffard O, Mollá P, Cavazza M & Prendinger H (2025) Enhancing large language models for bitcoin time series forecasting. Knowledge-Based Systems, 330 (Part A), p. 114449. https://doi.org/10.1016/j.knosys.2025.114449

Abstract
In the recent advancements in application of deep learning to time series forecasting, focus has shifted from training transformers end-to-end to efficiently leveraging the predictive capabilities of Large Language Models (LLMs). Models that encode the time series data to interact with a frozen LLM backbone have been shown to outperform transformers on all benchmark datasets. However, their efficiency on complex datasets, which do not show clear seasonality or trend, remains an open question. In this work, we seek to evaluate the performance of reprogrammed LLMs on the Bitcoin price chart, a financial time series known for its complexity and high volatility. We propose effective methods to improve the performance of Time-LLM, a State-of-the-art (SOTA) method, on such a time series. First, we propose structural improvements to Time-LLM. Second, we suggest an efficient way to handle the non-stationarity of the dataset. Finally, we propose an efficient method for passing additional financial information to the LLM. Our results demonstrate a 50 % improvement on the average percentage loss and a 5 % increase on accuracy of our adapted Time-LLM architecture on Bitcoin data when compared to SOTA models, including the original Time-LLM model. This highlights the impact on forecast accuracy of domain-specific decision making in data processing and feature selection.

Keywords
Time series forecasting; Language models; Financial time series

Journal
Knowledge-Based Systems: Volume 330, Issue Part A

• Chaffard-et-al