Compute · the Ledger · Capacity contract
OpenAI recapitalizes; Microsoft's stake is ~27% (~$135B) and OpenAI contracts to buy an incremental $250B of Azure services
Amended · announced 28 Oct 2025 · the week to 31 Oct 2025
- Size
- $250B
$250B incremental Azure purchase commitment; no term stated.
The parties
- OpenAIcompany pageBuyer
- Microsoftcompany pageProvider
- Microsoftcompany pageInvestor
The source
Microsoft blog, 2025-10-28Company press release
Microsoft's stake valued at ~$135B, ~27% on an as-converted diluted basis. Microsoft loses its right of first refusal as OpenAI's compute provider.
The same parties, other deals
- ChronoScale and Microsoft sign a three-year partnership for about 50 MW of planned AI compute capacityundisclosed · 19 Aug 2026
- Nvidia gives SB Energy residual value guaranties, capped at $105B, on ~4.25 GW of Ohio data center leases to OpenAI$105B · 17 Aug 2026
- Amazon agrees to invest $50B in OpenAI: $15B in the current round plus a $35B commitment tied to milestones or an IPO$50B · 27 Feb 2026
- OpenAI expands its AWS agreement by $100B over eight years, including ~2 GW of Trainium capacity$100B · 27 Feb 2026
- OpenAI agrees to deploy 750 MW of Cerebras inference compute; Cerebras's S-1 values the deal at more than $20B$20B · 14 Jan 2026
- Anthropic commits to $30B of Azure compute; Nvidia to invest up to $10B and Microsoft up to $5B in Anthropic$30B · 18 Nov 2025