Microsoft recorded a $3.2 billion gain on its Anthropic investment during the fourth quarter of fiscal 2026, boosting diluted earnings per share by 33 cents.

The tech giant invested $5 billion in Anthropic in November 2025 as part of a circular agreement where the AI safety lab committed to purchasing $30 billion worth of Azure cloud services.

Microsoft's OpenAI investment fared worse during the same period. The company marked down its OpenAI stake by approximately $600 million, reducing diluted earnings per share by 7 cents.

Microsoft owns roughly 27% of OpenAI and receives revenue-share payments from the ChatGPT maker, though it does not disclose the specific amounts under that arrangement.

Full-year performance tells different story

For the full fiscal year, Microsoft's OpenAI investment generated a $5 billion gain and added $0.67 to earnings per share. The annual performance contrasts sharply with the quarterly decline.

Microsoft reported $90 billion in quarterly revenue and net income of $35.8 billion for Q4. Full-year revenue reached $331.8 billion with net income of $133.7 billion.

The $600 million OpenAI write-down represents a relatively small impact on Microsoft's overall financial performance, which the company described as "highly profitable."

Microsoft does not routinely update the value of its Anthropic investment each quarter, making the $3.2 billion gain disclosure particularly noteworthy.

The contrasting performance of the two AI investments highlights the volatile nature of private market valuations in the rapidly evolving artificial intelligence sector. Both companies compete directly in the foundation model space, with Anthropic's Claude and OpenAI's GPT models vying for enterprise customers.

Microsoft will continue reporting on both investments as the AI market develops and valuations fluctuate with competitive dynamics and technological breakthroughs.