The business world is undergoing a radical transformation thanks to the increasingly widespread integration of AI agents in operational processes, from customer management to back-office operations, and even complex decision-making in financial and compliance areas. However, this rush to adopt artificial intelligence has highlighted a new challenge: while AI agents are indeed capable of retrieving information, they often struggle to provide coherent, explainable, and reliable reasoning, especially when faced with complex, multi-step, or high-risk tasks. To address this need, Sentient, an open-source artificial intelligence lab, has launched Arena: a live testing environment designed to stress-test the most advanced AI solutions and evaluate their reasoning capabilities in real business contexts. Arena aims to be a global meeting point for developers, investors, and companies, involving from the very first phase prominent names such as Founders Fund, Pantera, Franklin Templeton (with over $1.5 trillion in assets under management), alphaXiv, Fireworks, and OpenRouter.