In the fourth quarter Microsoft’s Anthropic investment produced a $3.2 billion gain while its OpenAI position was marked down by roughly $600 million, against a $5 billion gain on that same OpenAI position for the full year. Two frontier lab stakes, held by one company, moving $3.8 billion in opposite directions inside ninety days. There is no operating business inside Microsoft that swings that hard that fast, which makes the other income line the most volatile input in the model and the least analyzed.

Microsoft reported fourth-quarter capital expenditure of $41 billion, up 70% year over year, and simultaneously lowered its 2026 capex forecast to $175 billion from $190 billion. The company was explicit that spending plans have not changed. An accounting change did. That combination deserves more attention than it will get, because a $15 billion reduction in a guidance figure that everyone on the street uses as a proxy for compute added is not a reduction in compute added.