What share of cloud backlogs comes from OpenAI and Anthropic?
About half, as of the last direct report in May 2026. The Information put OpenAI and Anthropic at around half of about $2 trillion across Amazon, Microsoft, Google and Oracle. Counting only contracts we can source, against the latest and larger backlogs, we get about 39 percent, which we treat as a rough floor.
No cloud provider publishes this split in full. The 39 percent is our own floor, built from mixed dates. Data as of 2026-11-05.
Our count: disclosed lab contracts against the latest backlogs
| Cloud | Latest backlog | OpenAI contracts | Anthropic contracts | Sources |
|---|---|---|---|---|
| Microsoft | $677B (Sept 2026) | $250B | $31.4B | 24/7 Wall St., 2026-10-28 The Register, 2026-01-29 Business Day / Reuters, 2026-09-29 |
| Oracle | $664B (Aug 2026) | About $300B | None found | Oracle via SEC EDGAR, 2026-08-31 DatacenterDynamics, 2025-09 |
| Amazon (AWS) | $578B (Sept 2026, secondary) | $138B | $110B | AI Weekly (citing CNBC), 2026-10-29 GeekWire, 2026-02-27 Business Day / Reuters, 2026-09-29 |
| Google Cloud | $514B (June 2026) | None found | At least $111.1B | W.Media, 2026-07-23 Business Day / Reuters, 2026-09-29 |
| Total | About $2.43T | $688B | $252.5B | Our sum |
Together the labs come to about $940B, or 39 percent of the total (our arithmetic). Using The Information's reported $200B for Anthropic at Google instead gives about 42 percent. Contract values may not match the amounts booked in backlog, and the dates differ, so treat this as a rough floor.
What each company has said
Microsoft said about 45 percent of its $625 billion backlog at December 31, 2025 was attributable to OpenAI. The Register, 2026-01-29 Oracle's share is estimated at roughly half of $664 billion. ERP Today, 2026-09-11 The Information reported in May 2026 that OpenAI and Anthropic were about half of AWS's backlog, and that OpenAI accounted for more than 80 percent of the increase in its first-quarter backlog. Michael Parekh (AI-RTZ Substack), 2026-05-07
The share may be falling
Microsoft says the roughly $50 billion rise in its backlog in April to June 2026 came from customers outside the leading AI labs. The Standard (Hong Kong), reprinting Reuters, 2026-07-30 Oracle's non-OpenAI backlog more than doubled in a year. ERP Today, 2026-09-11 So the 45 percent is dated, and Microsoft's current share is probably lower.
A caution on the totals
Anthropic's public S-1 tally is larger than the amounts counted here, at about $657 billion. Fortune, 2026-10-27 Much of it runs through suppliers outside these four clouds, including equipment leases for Broadcom-built systems, SpaceX's xAI, AMD and smaller GPU rental firms. Those deals are outside this table. Business Day / Reuters, 2026-09-29
Our read
This section is our judgment, kept separate from the sourced record above.
Either way, two private companies that depend on outside money account for somewhere between two-fifths and a half of the largest cloud order books in the world. That is concentration of contracts, not necessarily of end demand: behind the labs are their own paying customers.
Backlog is a weaker signal than it looks, because the two biggest customers have not yet shown they can fund all of it from their own revenue.
What would change this answer
- Google Cloud's and AWS's next disclosed backlogs
- Any updated OpenAI share from Microsoft
- Oracle's next quarterly backlog and its non-OpenAI part