Arena Launches Alignment Index and Closes $200M Series B as Agent Safety Evaluation Becomes Critical

Arena, the AI evaluation platform regarded as the gold standard for benchmarking frontier models, announced the Alignment Index on October 8, 2026—a new leaderboard that measures AI agent safety and reliability by tracking real-world behavioral failures rather than benchmark scores alone. Simultaneously, the company closed a $200 million Series B round at a valuation near $3 billion, more than doubling its $1.7 billion valuation from its previous funding.