Lightspeed Venture Partners and Khosla Ventures co-led the round; Salesforce Ventures, 01 Advisors, Dell Technologies Capital, Acrew Capital, and Endeavor Catalyst also participated. Arena says it has exceeded $100 million in annualized revenue.
Alongside the financing, the company released a preview of its Arena Alignment Index. The index evaluates agent behavior in real-world traces using three signals: Unauthorized Action, False Attribution, and Deceptive Completion. Arena says it has published methodology and initial results for more than 20 frontier models.
Arena reports that Agent Arena reached 7 million sessions in under five months, while the wider platform has recorded 350 million sessions and 62 million votes. It also says it has open-sourced 375,000 data points and tracks more than 1,000 model evaluations.
The announcement does not independently verify Arena’s revenue, platform metrics, valuation, or the validity and generalizability of the Alignment Index results. It does not state commercial access terms or pricing for the index.