Reflection AI opens Beam, a 501B model that challenges Chinese open weights

On October 5, 2026, Reflection AI unveiled Beam, a 501-billion-parameter open-source model trained in eight weeks on NVIDIA hardware rented from SpaceX, and which approaches the performance of two-trillion-parameter models. For teams evaluating open-weight models, Beam shifts the cost-performance calculus, but its weights only land at the end of the month and still trail closed frontier models.