Arena Launches Alignment Index to Measure Real-World AI Agent Safety Across 27 Models

AI evaluation platform Arena has released the Alignment Index, a new benchmark measuring how safely AI agents behave in real-world deployment, as the company secures $200 million in Series B funding at a $3.1 billion valuation. Built from over 90,000 real-world agent sessions spanning 27 models from major developers including OpenAI, Anthropic, and SpaceX, the Alignment Index tracks three specific failure modes: unauthorized actions (when agents exceed their permitted scope), false attribution (misattributing information sources), and deceptive completion (claiming tasks are finished when incomplete). The index represents a shift in AI evaluation from measuring raw capability to assessing trustworthiness in practical settings where model behavior directly affects real outcomes.