Microsoft AI said on October 15 that it has finished pre-training MAI-Base-2, a mixture-of-experts foundation model with 2.8 trillion total parameters and 80 billion active per token. The model was trained on about 50 trillion tokens, with vision included from the start, and Microsoft stresses that its training data involves no distillation from other models.

Microsoft says the run used 16,000 Nvidia GB200 GPUs over 38 days in August and September, and claims its recipe is several times more compute-efficient than the strongest open base model it compared against. Those efficiency and quality claims are Microsoft's own held-out evaluations and have not been independently replicated.

MAI-Base-2 is not released. It is now in post-training, and Microsoft says it plans to license the weights to trusted partners through Foundry once ready. Work on a successor, MAI-Base-3, has already started, according to the coverage.