On October 8, 2026, Arena, the company formerly known as LMArena that runs the crowdsourced head-to-head model leaderboard, announced a $200 million Series B at a $3.1 billion valuation. The round was co-led by Lightspeed Venture Partners and Khosla Ventures, with Salesforce Ventures, 01 Advisors, Dell Technologies Capital, Acrew Capital and Endeavor Catalyst joining, and existing investors including a16z, Felicis, AMP PBC, QuantumLight and The House Fund participating.
In the announcement, Arena said it had raised its Series A in January 2026 and has since “exceeded $100M in annualized revenue,” growing into a platform that evaluates agentic capabilities across many kinds of work. Its revenue comes largely from selling evaluations to model developers and enterprises. Alongside the round it introduced the Arena Alignment Index, which it describes as a new measurement of how well frontier models act in line with human intent.
Arena began as Chatbot Arena, a UC Berkeley research project in 2023 that ranked chat models by pairwise human votes. Its leaderboard became one of the most watched scoreboards in the industry, and labs routinely cite its rankings when launching models.
Why it matters: evaluation has become a business in its own right. A research leaderboard turning into a $3.1 billion company with nine-figure revenue shows how much model makers and buyers will pay for an outside view of which model is better.
What it does not show: the revenue figure is company-stated and unaudited. The valuation does not settle long-running questions about whether crowdsourced preference votes measure real capability, or about conflicts when the labs being ranked are also paying customers.