Arena Raises $200M Series B to Scale AI Agent Safety Evaluation Platform

Arena, the AI evaluation platform founded as a UC Berkeley research project, has closed a $200 million Series B round at a $3.1 billion post-money valuation, marking a rapid expansion of its mission to measure real-world AI agent safety. The funding round, led by Lightspeed Venture Partners and Khosla Ventures and joined by Salesforce Ventures, 01 Advisors, Dell Technologies Capital, Acrew Capital, and Endeavor Catalyst, arrives as the company simultaneously unveiled the Arena Alignment Index—a production-scale benchmark assessing how safely AI agents behave when deployed in enterprise environments.