Arena raises $200 million at a $3.1 billion valuation, unveils Alignment Index preview

Arena announced a $200 million Series B at a $3.1 billion valuation, co-led by Lightspeed Venture Partners and Khosla Ventures. The company also introduced a preview of its Alignment Index, which it says compares 27 AI models across 90,000 real-world agent sessions for unauthorized actions, false attributions to users and claims that unfinished tasks are complete.