TLDR
- Microsoft stock closed at $502.45 on September 9, rising 0.81%, with pre-market shares at $503.00.
- Diversifies AI strategy by integrating Anthropic’s Claude Sonnet 4 into Office 365 apps.
- Signs $20B deal with Nebius to lease GPU-based AI computing power over five years.
- Q4 capex on AI expected to reach $120B, nearly quadruple 2023 levels.
- OpenAI partnership continues, though rifts emerge as both firms pursue independence.
On September 9, Microsoft Corporation (NASDAQ: MSFT) stock closed at $502.45, up 0.81%, with pre-market shares moving higher to $503.00.
The company announced a major shift in its AI strategy by integrating Anthropic’s models into Office 365 apps, reducing reliance on OpenAI.
Anthropic’s Claude Sonnet 4 will support tasks such as creating visually compelling PowerPoint presentations and advanced financial functions in Excel. Microsoft leaders believe Claude outperforms OpenAI’s models in specific areas, signaling a diversification of its productivity AI tools.
This decision comes as Microsoft negotiates a new agreement with OpenAI, while also investing in its own AI models such as MAI-Voice-1 and MAI-1-preview. The move underscores the company’s desire for self-reliance in the rapidly evolving AI landscape.
Ongoing Relationship with OpenAI
Despite the new collaboration, Microsoft confirmed it remains committed to its long-term partnership with OpenAI, where it has invested more than $13 billion. OpenAI’s GPT-5 continues to power parts of Microsoft’s AI ecosystem, though OpenAI itself is seeking independence by building AI chips with Broadcom and launching competing products like a jobs platform rivaling LinkedIn.
Tensions have surfaced as OpenAI pursues infrastructure beyond Microsoft’s Azure cloud. Yet, Microsoft reiterated that OpenAI will remain central to frontier model development while Anthropic complements its broader AI mix.
$20 Billion Nebius Deal
Alongside Anthropic integration, Microsoft signed a five-year deal worth up to $20 billion with Nebius, an AI infrastructure provider spun off from Yandex’s international operations. The agreement secures GPU computing power at Nebius’s new data center in New Jersey, crucial for training and deploying large-scale AI models.
Nebius valued the contract at $17.4 billion, with the potential to expand to $19.4 billion based on Microsoft’s demand. The company plans to finance its data centers through cash flow from the deal and debt secured against the contract.
Shares of Nebius surged 68% in after-hours trading following the announcement, while rival CoreWeave rose more than 5% as investors viewed the deal as a signal of sustained AI infrastructure demand.
Rising AI Investments
Microsoft has significantly increased its capital spending on AI, projecting $120 billion in 2025, compared to $88 billion in 2024 and just $32 billion in 2023. The company has also signed multiple infrastructure contracts, including up to $10 billion with CoreWeave, to ensure it can meet the growing demand for AI services.
This surge highlights the scale of competition in AI cloud infrastructure, where companies like Nebius, CoreWeave, and Mistral are quickly scaling up to meet the needs of major tech firms.
