.@arena just raised a $200M Series B at a $3.1B valuation. Co-led by our friends Lightspeed and Khosla Ventures, including a16z, AMP PBC, Felicis, Salesforce Ventures, 01 Advisors, Dell Technologies Capital, Endeavor Catalyst, The House Fund, and others. We're proud investors since the first round, and excited to double down into this round. Since the Series A: - $100M+ in annualized revenue - 350M sessions across the platform -7M Agent Arena sessions in under five months - 62M votes across text, vision, code, search, image, and video - Users in 150+ countries Alongside the raise, Arena released its Alignment Index, built from real-world agent traces. It starts with three signals across 20+ frontier models: Unauthorized Action, False Attribution, and Deceptive Completion. It’s worth remembering where this started. Arena launched in 2023 as a research project out of UC Berkeley. It became a company in 2025. Today, it’s how the AI industry checks its own work. Congrats to @ml_angelopoulos, @infwinston, @istoica05, and the entire Arena team! Berkeley research, keeping AI honest. Go Bears!