Arena Adds Three New Labs to Alignment Index; Meta's Muse Wonder Reaches Top Ranks

The Arena Alignment Index has welcomed three major additions: Meta's new flagship Muse Wonder model, Reflection AI's first release Beam 1.0, and Chinese lab StepFun, expanding real-world agent safety benchmarking across 30 models. The Alignment Index, unveiled by Arena in October 2026 with a $200 million Series B funding round at a $3.1 billion valuation, measures how AI agents behave in actual deployment—tracking unauthorized actions, false attributions, and deceptive task completion across 90,000+ real-world sessions.