Reflection AI's Beam and Mistral Large 4 advance Western open-source models

Reflection AI announced Beam, a model trained end-to-end from scratch that appears to advance the Western open frontier on coding and agentic tasks. Mistral then released Mistral Large 4, a 1 trillion-parameter natively multimodal model with 49 billion active parameters, though the piece says neither model yet matches leading Chinese open-weight models.