The article introduces Beam, a sparse Mixture-of-Experts model with 501 billion total parameters, built for coding, reasoning, and agentic workloads. Beam's capabilities come from major investments in pretraining and reinforcement learning, with a focus on efficient reasoning and coding performance. The model is undergoing final evaluations and will be released as open weights later this month. Beam's performance is competitive with larger open models, with an advantage in efficiency at inference time.