Microsoft finishes pre-training MAI-Base-2, its next in-house foundation model

Microsoft has finished pre-training MAI-Base-2, the next foundation model from its in-house AI group. Pre-training is the most compute-intensive stretch of building a large language model. It produces the raw intelligence, not the polished product, and it signals that Microsoft’s homegrown AI effort is moving into its second generation. What finishing pre-training actually means Think of pre-training as a model’s undergraduate degree. It reads a vast library of text and learns to predict what comes next, picking up grammar, facts and patterns along the way. What it can’t do yet is follow instructions gracefully or reason through a problem on request. Those skills come in later phases, typically called mid-training and post-training, where the raw model gets shaped into something people can actually use. The name gives a hint about where it fits. Its predecessor, MAI-Base-1, is the base model underneath MAI-Thinking-1, the flagship reasoning model Microsoft AI introduced earlier this year. MAI-Base-1 set a high bar on scale. It was pre-trained on 30 trillion tokens of clean, human-generated data, then went through another 3.55 trillion tokens during mid-training. The hardware was eq...