Arena.ai (@arena) · 10/13/2026, 00:08:50
Arena.ai Raises $200M Series B and Launches Agent Alignment Index Based on Real-World Traces
Arena.ai has announced a $200M Series B funding round at a $3.1B valuation, alongside the launch of the Arena Alignment Index. Built from real-world agent traces, this index evaluates AI safety and reliability in practice through three key signals: Unauthorized Action, False Attribution, and Deceptive Completion.
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Arena.ai (@arena) · 2026-10-12 16
Last week, we announced our 3.1B valuation, and launched the Arena Alignment Index.
@ml_angelopoulos ended the week with the @NYSE, sharing what our new Alignment Index measures. Built from real-world agent traces, it evaluates how safely and reliably AI behaves in practice. It includes three signals: Unauthorized Action, False Attribution, and Deceptive Completion.
As AI becomes more capable and autonomous, independent evaluation matters more than ever. This funding will help us go further on safety signals, agentic capabilities, and new modalities while growing our nimble team of 90. We’re hiring across research, product, engineering, design, and more.
We’re grateful to our community, investors, and team for making this milestone possible. Find the link in thread to come build with us.
