We're excited to announce a major milestone for Arena: our $200M Series B at a $3.1B valuation, accelerating our mission to measure and advance frontier intelligence! At Arena, we believe AI evaluation must be grounded in real-world use. We put agents in live tool-use environments, challenge them with complex, long-horizon tasks, and analyze rich signals from millions of real-world user-agent interactions to understand how they perform. Today, we're also introducing the Arena Alignment Index, extending our evaluations beyond capability to measure how safely, reliably, and faithfully agents act in accordance with human intent. As AI systems become increasingly autonomous, evaluating what they can do is no longer enough. Understanding whether they reliably follow human intent, navigate uncertainty, and act safely in real-world environments is becoming one of the most important challenges in AI. We're excited to continue advancing the research and building the infrastructure needed to rigorously measure both capability and alignment at the frontier of AI. If you’re passionate about this mission, come build with us!