Arena raises $200M Series B at $3.1B valuation
Arena closed a $200 million Series B led by Lightspeed and Khosla Ventures, and added an alignment category to its model leaderboard.
Arena has raised a $200 million Series B round at a $3.1 billion valuation, according to TechCrunch. The round was led by Lightspeed Venture Partners and Khosla Ventures.
Salesforce Ventures, 01 Advisors, Dell Technologies Capital, Endeavor Catalyst, a16z and Felicis also joined the round.
The company also added an alignment category to its leaderboard. That leaderboard ranks models on issues including unauthorized action, false attribution and deceptive completion.
OpenAI models currently top Arena's preliminary alignment leaderboard, while Claude Opus 5.5 and Claude Fable rank sixth and ninth respectively.
From Berkeley project to commercial product
Arena began in 2023 as a research project at UC Berkeley that crowdsourced rankings of AI models. In September 2025 it introduced its commercial product, AI Evaluations, offering model labs and enterprises performance analytics based on community feedback.
In January the company announced a $150 million Series A at a $1.7 billion post-money valuation, when its annualized revenue stood at $30 million. In June, Arena said it reached $100 million in annualized run-rate revenue.
Quick answers
How much did Arena raise in its Series B?
Arena raised $200 million at a $3.1 billion valuation.
Which models top Arena's alignment leaderboard?
OpenAI models currently top the preliminary alignment leaderboard, with Claude Opus 5.5 and Claude Fable in sixth and ninth place.