Title: AlphaFormer: End-to-End Symbolic Regression of Alpha Factors with Transformers
Primary area: learning on time series and dynamical systems
Keywords: Symbolic Regression, Alpha Mining, Time Series Generative Modeling

Abstract: Identifying predictive patterns for stock market trends, known as alpha factors, is a critical challenge in quantitative finance. Symbolic regression (SR) methods can discover these factors as interpretable mathematical expressions, offering advantages over ``black-box'' machine learning approaches and manual methods that rely heavily on human expertise. However, existing SR methods typically restart the discovery process for each new dataset, failing to leverage prior knowledge. To address this limitation, we propose AlphaFormer, an encoder-decoder Transformer model designed for the end-to-end generation of synergistic alpha factors from raw stock market data. AlphaFormer leverages pre-training on synthetic datasets to efficiently uncover synergistic alpha factors for new datasets, capitalizing on acquired prior knowledge. To overcome the challenge of generating synthetic stock datasets with temporal dependencies, we introduce a novel generative framework that integrates multiple time-series generative models to generate synthetic stock data and dynamically select the highest quality samples, ensuring the creation of high-fidelity datasets crucial for pre-training. Extensive evaluations on real-world stock market datasets demonstrate that AlphaFormer outperforms existing methods across widely used metrics, achieving superior performance with significantly reduced inference computation---generating only 33\% as many factors as the best baseline and requiring no further training during inference. Backtests further show that AlphaFormer delivers the highest annual return among all methods, highlighting its practical potential for superior investment performance.

TL;DR: We propose AlphaFormer, an encoder-decoder Transformer model specifically designed for the end-to-end generation of synergistic alpha factors from raw stock market data.