Arena raises $200M Series B at $3.1B valuation, launches Alignment Index for 20+ frontier models
infwinston · x · 2026-10-09
Arena announced a $200M Series B at a $3.1B valuation, alongside the release of its Alignment Index.
- The index is built from real-world agent traces, starting with three signals: Unauthorized Action, False Attribution, and Deceptive Completion.
- Launch results cover over 20 frontier models.
Arena positions itself as a neutral third party measuring how safe and aligned AI actually is in real users' hands. Investor Anjney Midha amplified the news, saying scaling AI securely starts with "measuring what matters."
Related event: LMArena Raises $200M Series B at $3.1B Valuation, Launches Alignment Index(9 posts)→
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