Arena, formerly LMArena, operates the Chatbot Arena, a public leaderboard that ranks AI models using crowdsourced human preference votes. The project began in 2023 as an academic effort at UC Berkeley under the LMSYS research organization, was incorporated as a company in April 2025, and was rebranded as Arena in January 2026. Anastasios Angelopoulos is co-founder and CEO, and co-founders include Wei-Lin Chiang and Ion Stoica.
TechCrunch reported on October 8, 2026 that Arena raised a $200 million Series B at a $3.1 billion valuation, nearly double its valuation from ten months earlier. Lightspeed Venture Partners and Khosla Ventures led the round, with Salesforce Ventures, 01 Advisors, Dell Technologies Capital, Endeavor Catalyst, a16z and Felicis participating. It followed a $100 million seed in May 2025 and a $150 million Series A in January 2026 at a $1.7 billion valuation.