Arena raises $200M to grow its AI leaderboard

Arena raised a $200 million Series B at a $3.1 billion valuation, led by Lightspeed Venture Partners and Khosla Ventures. That nearly doubles its $1.7 billion Series A valuation from January 2026. The Berkeley-started site ranks AI models by user votes, draws tens of millions of monthly visitors, and sells testing services to AI labs and businesses.