Microsoft posted blockbuster fourth-quarter results for its fiscal 2026 year, which ended on June 30, and tucked away a notable detail about how its stakes in the two largest—and competing—AI labs are performing. During the quarter, the company recorded a $3.2 billion gain from its investment in Anthropic, which added 33 cents to diluted earnings per share. (Microsoft reported diluted EPS of $4.81 for the quarter.) The tech giant invested $5 billion in Anthropic in November 2025 as part of a circular arrangement where the AI lab also agreed to purchase $30 billion worth of Azure services.

Microsoft doesn't regularly reassess the value of its Anthropic investment each quarter. However, it does provide quarterly updates on its OpenAI stake. Microsoft said that investment didn't fare nearly as well during the period, with a markdown of about $600 million, reducing diluted EPS by roughly 7 cents per share. Microsoft owns approximately 27% of OpenAI. While the company also receives revenue-sharing payments from OpenAI, it doesn't disclose how much the AI lab pays under that agreement. Instead, Microsoft accounts for the value of its investment.

Although this quarter saw a sizable decline in the value of that OpenAI stake, the $600 million write-down was largely a rounding error for Microsoft. The company delivered a highly profitable quarter, reporting $90 billion in revenue and net income of $35.8 billion. For the full fiscal year, Microsoft's revenue reached $331.8 billion, with net income of $133.7 billion.

Microsoft's OpenAI investment looks significantly better when viewed over the full year. For the fiscal year, the OpenAI stake generated a $5 billion gain and added $0.67 to earnings per share, the company reported. (Microsoft reported $17.95 EPS for its fiscal year.) Still, it's noteworthy that Microsoft reported nearly as much of a gain from Anthropic in a single quarter as it did from OpenAI for the entire year. In fact, this is so striking that Microsoft chose to disclose it.