Microsoft logs $3.2B from Anthropic investment, but OpenAI was a mixed bag

Microsoft recorded a $3.2 billion gain on its Anthropic investment in the fourth quarter of fiscal 2026, which it obtained after investing $5 billion in November 2025. The company's investment in OpenAI, by contrast, was marked down by about $600 million in the same quarter, though it generated a $5 billion gain for the full year. Microsoft owns about 27 percent of OpenAI and accounts for the value of its investment quarterly, while it does not routinely update its Anthropic valuation each quarter. The notable difference between the two investments is significant enough that Microsoft disclosed it despite the $600 million OpenAI decline being relatively minor in the context of the company's overall highly profitable quarter.