RealFin: How Well Do LLMs Reason About Finance When Users Leave Things Unsaid?

Researchers at the arXiv open-access repository published a study on February 11, 2025, introducing RealFin, a new bilingual benchmark designed to measure the financial reasoning capabilities of Large Language Models (LLMs) when faced with underspecified or incomplete data. Developed to address the industry's reliance on implicit assumptions, the benchmark tests whether AI systems can identify when a financial problem lacks sufficient information to reach a definitive conclusion. This initiative comes as financial institutions increasingly integrate AI into decision-making processes, necessitating tools that can prevent models from 'hallucinating' answers to logically unanswerable queries. The RealFin benchmark focuses on a critical gap in current AI evaluation: the difference between rote calculation and contextual understanding. In professional financial services, experts often operate with shared knowledge that is rarely explicitly stated in a prompt. When these essential details are missing, traditional AI models often attempt to provide a concrete answer regardless of its validity. RealFin addresses this by systematically removing essential pieces of information from financial scenarios, challenging models to recognize their own limitations and withhold judgment rather than providing potentially misleading or inaccurate financial advice. Technically, the study highlights how bilingual reasoning—covering both English and Chinese—is essential for capturing the nuances of global financial markets. By evaluating how models handle missing variables across different languages and regulatory contexts, the researchers aim to foster the development of more robust, transparent, and reliable AI systems. Ultimately, the RealFin framework provides a standardized method for ensuring that the next generation of financial AI can navigate the complexities of real-world practice, where knowing 'what you don't know' is just as valuable as knowing the correct answer.