Microsoft MAI-Base-2: 2.8T Params, 12x DeepSeek Gain

Microsoft AI said on October 15, 2026, that it had finished pre-training MAI-Base-2, an in-house foundation model built with 2.8 trillion total parameters and 80 billion active parameters. The company framed the run as a turning point: a mixture-of-experts model trained on 16,000 Nvidia GB200 GPUs over 38 days that, by Microsoft’s own account, beat every open-weight model it tested and did so using a training recipe the company calls 4 to 12 times more compute-efficient than DeepSeek-V4-Pro-Base. Separately, Microsoft AI CEO Mustafa Suleyman reportedly told staff at an internal town hall that early tests showed MAI-Base-2 outperforming the base model behind OpenAI’s GPT-5.6 Sol on pattern-understanding and prediction tasks, while using roughly a quarter of OpenAI’s pre-training compute.