Reflection previews Beam, a 501B-parameter open agentic model

Reflection AI previewed Beam, an MoE open model with 501B total and 23B active parameters, claiming 3–4x better inference efficiency than GLM 5.2.

The model was pretrained from scratch on 23.8T tokens in four weeks, and its RL run used 10,500 GB300 GPUs over four weeks, which the post describes as possibly the largest publicly recorded.

Reflection positions Beam as a workhorse open model for enterprises, governments, and developers, with full weights due this month.