Four days after Anthropic filed to go public, the argument over its prospectus has moved from Anthropic's own numbers to the companies its spending pays. Its Form S-1 names seven compute suppliers with fixed or capped amounts that add up to $637 billion, on SaasBuzz's count, and the suppliers' own filings show how much of their own business those deals have become.
The sharpest case is SpaceX (Nasdaq: SPCX). Its third-quarter 10-Q says one customer, "Customer B," was 34.5% of its revenue, and Bloomberg reported on October 29, citing a person familiar with the matter, that Customer B is Anthropic. That is about $5.0 billion in one quarter, by our calculation. Anthropic's minimum commitments to Google (Nasdaq: GOOGL) and Amazon (Nasdaq: AMZN), meanwhile, equal about a fifth of the backlog each of those companies reported for September 30. Anthropic's IPO is also a test of its suppliers.
Who the compute deals pay
The S-1 lists the agreements one by one. Anthropic committed to spend at least $114.5 billion with Google between April 2026 and July 2033 and at least $110.0 billion with Amazon between May 2026 and April 2036, "regardless of actual usage," paying the difference as a true-up if it falls short. Microsoft (Nasdaq: MSFT) gets at least $44.9 billion from November 2026. SpaceX's subsidiary SpaceXAI gets up to $120.5 billion, Nscale up to $44.6 billion and Lambda about $41.3 billion, all for capacity on Nvidia GPUs. Five-year equipment leases with Broadcom (Nasdaq: AVGO) carry about $161.2 billion of rent for TPU-based capacity.
We set each commitment against the backlog the supplier itself reports. The comparison is one of scale: no supplier says how much of its backlog is Anthropic.
Supplier | Anthropic | Backlog | Share |
|---|---|---|---|
$114.5B | $560.8B | 20% | |
Amazon | $110.0B | $578B | 19% |
Microsoft | $44.9B | $677B | 7% |
Nscale | $44.6B | $103.4B | 43% |
SpaceX | $120.5B | $63.0B | 191% |
Source: SaasBuzz analysis of Anthropic's S-1 and the suppliers' filings. Backlog is Google Cloud's at September 30 (Alphabet 10-Q), Amazon's unrecognized long-term commitments, "primarily related to AWS" (Amazon 10-Q), Microsoft's commercial remaining performance obligation (Microsoft 10-Q), Nscale's contracted value at August 31 and SpaceX's total backlog. Anthropic's Nscale and SpaceX figures are ceilings.
Google's TPU chip is the largest single destination once the Broadcom leases are counted, because those leases buy TPU-based capacity, though the rent is paid to Broadcom. Together the two come to $275.7 billion, 43% of the seven named amounts. The S-1 adds an estimated $125 billion to $150 billion for more TPU compute from 2028 to 2031, outside its commitments table.
Amazon's exposure runs both ways. Its 10-Q, filed October 30, carries its Anthropic preferred stock at $92.5 billion and its Anthropic convertible notes at $146.2 billion, together 80% of the $298.8 billion Amazon records for all its equity and debt investments. It booked $62.8 billion of upward adjustments on the preferred stock in the first nine months of the year. We covered the rest of Amazon's quarter separately.
SpaceX: one customer, a third of revenue
SpaceX's filing does not name Anthropic. It says Customer B's revenue "relates to the SI segment," short for Super Intelligence, which holds its AI infrastructure business along with Grok, Cursor and X, and that the segment's revenue rose to $7.56 billion from $813 million a year earlier. On our math Customer B accounted for about $5.0 billion of revenue, two-thirds of the segment and equal to 90% of Anthropic's entire $5.56 billion compute and infrastructure expense in the second quarter.
The deal is still ramping. Anthropic's S-1 puts the SpaceXAI arrangements at about $3.1 billion a month once all capacity is delivered, which it expects in December, with "different fees during capacity ramping periods." That is 1.8 times Customer B's monthly revenue in the third quarter. But after initial periods ending in January and March 2027, either side can cancel on 90 days' notice. SpaceX's whole backlog, which counts only enforceable agreements, was $63.0 billion at September 30, about half the deal's $120.5 billion ceiling. Bloomberg's headline called it "a finite deal." Neither company had confirmed the identification publicly by 9:45 a.m. ET.
Nscale needs financing, and Nvidia may provide it
The Nscale agreements depend on money Nscale did not have when it filed. Anthropic's S-1 says Nscale "is required to use best efforts to obtain qualifying financing" for the GPUs and data centers. Nscale's own S-1, filed September 18, says Anthropic's contracts are worth up to $44.6 billion, equal on our math to 43% of its $103.4 billion contracted value, and that it had "not obtained binding commitments for any of the financings required" to perform them.
On October 29 The Information reported that Nvidia (Nasdaq: NVDA) is in talks to give Nscale billions of dollars in credit guarantees for the West Virginia campus Anthropic plans to use. Reuters, carrying the report, said the deal had not been signed and the terms could change. If it goes ahead, the chip supplier would be backing the debt of a customer whose largest contract is with Anthropic.
The growth debate
The bill only works if revenue keeps outrunning it. The S-1's quarterly table shows revenue up 132% from the fourth quarter to the first and 144% from the first to the second, to $11.56 billion. Revenue per dollar of compute and infrastructure expense rose from 0.40 at the start of 2025 to 2.08 in the second quarter. Anthropic's explanation is in the filing: it buys compute "12 to 18 months in advance of availability," so the cost is "generally fixed in the near term."
The S-1 leaves third-quarter revenue blank, and it also leaves a blank for run-rate revenue "as of October 31, 2026." Steve Eisman, host of the podcast The Real Eisman Playbook, said on his podcast that sequential growth fell from 147% to 45% in the third quarter, 24/7 Wall St. reported. The 45% came from an attendee at an investor day, and Anthropic declined to comment, the outlet said. If it is right, third-quarter revenue was about $16.8 billion. Eisman's own estimate puts revenue per compute dollar at 1.7, still above the first quarter's 1.40.
Gavin Baker, chief investment officer of Atreides Management, argued on X the day the S-1 went public that price cuts had likely turned growth sharply up again in October:
Post on X by @GavinSBaker
I am shocked, absolutely shocked, that Anthropic ARR has likely gone vertical in October after they cut token prices. Except the exact same thing happened for the entire AI market, which is why GPU rental prices have surged while token prices declined. $100b plus in year-end ARR looks possible again.
What the industry is saying
Anthropic itself has said little beyond the filing, as companies in registration usually do. Its own post on X announced the S-1 with a legal disclaimer:
Post on X by @AnthropicAI
Anthropic has filed an S-1 registration statement with the SEC related to its proposed IPO. Read more: https://www.anthropic.com/news/s1-sec Legal disclaimer: A registration statement relating to these securities has been filed with the SEC but has not yet become effective. These securities may not be sold, nor may offers to buy be accepted, prior to the time the registration statement becomes effective. This post does not constitute an offer to sell or the solicitation of an offer to buy these securities, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.
The sharpest skeptics read the same pages differently. Ed Zitron, who writes the newsletter Where's Your Ed At, called the profitable quarter a product of cheap compute and payment timing:
Post on X by @edzitron
The Anthropic S-1 tells a story of a company that scraped together a profitable quarter through discounted SpaceX compute and delayed payment terms for $430bn in non-cancellable contracts. It intentionally omits its Q3 2026 numbers. https://www.wheresyoured.at/exit-liquidity/
The S-1 does not give the SpaceXAI ramp fees, so the discount claim cannot be checked from the filing. Its operating income of $974 million in the second quarter is reported under GAAP.
From the buyer's side, Aaron Levie, chief executive of Box, pointed to the S-1's line that Anthropic's revenue from its Fortune 500 customers averaged "less than 0.1% of their total expenses" in the third quarter:
Post on X by @levie
This is the key stat. The average Fortune 500 customer of Anthropic spends less than .1% of their expenses on Anthropic. While that number likely will eventually asymptote somewhere (token prices coming down, and other large enterprise spend areas not going away), there’s no reason it can’t be 10-50X higher than this, reaching a “mere” 1-5% of spend. Which would still be a fraction of what most startups are spending. Thus, you can see how big of a divide there is between the frontier users of AI and the rest of the world still. Today, only a microscopically small set of companies are actually using agents for large amounts of background tasks and inside of workflows that aren’t human prompted. This Fortune 500 spend is likely dominated by coding tasks and broad employee productivity use-cases. But the big jump will come as these enterprises start to rewire their underlying processes for agents, which we’re now in the earliest stages of seeing. Agents processing large amounts of data in the enterprises; swarms doing coding, bio research, cyber, and other large fan out tasks; background workflows executing tasks in processes, and so on. All of these use cases generally are 100X bigger consumers of tokens, and much closer to direct ROI on the spend. This S-1 gives you a sense of both the strength of the frontier lab business model - even amidst massive competition - and how early we are in the build out of AI.
What it means for suppliers, buyers and investors
For investors in Alphabet, Amazon and SpaceX, Anthropic's offering prices a customer that already sits inside their reported growth. A fifth of Google Cloud's backlog and of Amazon's unrecognized commitments is roughly what Anthropic has promised each, and two-thirds of SpaceX's AI revenue last quarter came from one customer Bloomberg says is Anthropic. The S-1 names the tangle itself: Amazon, Google and Microsoft "have made significant equity investments in our company," and "these CSPs are also our customers." We traced how the cloud companies are paying for their buildout in our capex analysis.
The strongest counter-case is that suppliers are protected. The Google and Amazon agreements are take-or-pay with a true-up, so a slowdown at Anthropic does not cancel the revenue, and Anthropic held $112.4 billion in cash and $19.3 billion in short-term investments at June 30. That holds for Google, Amazon and Microsoft. It holds less for SpaceX, whose agreements become cancelable in early 2027, and for Nscale, whose contract waits on financing. And the protection is only as good as Anthropic's ability to pay up to $637 billion over the next decade, which is what public investors will now price.
For buyers of Claude, the bill cuts both ways. Anthropic buys capacity 12 to 18 months ahead, and Baker credits October's growth to cuts in token prices; those purchases also commit the company to fill that capacity, a risk its S-1 states plainly: it "may be committed to excess compute that remains underutilized."
What would change the picture: the amended S-1 with third-quarter revenue and the October 31 run-rate; SpaceX's fourth quarter, with full SpaceXAI capacity and the $3.1 billion monthly rate expected from December; whether Nscale's financing is signed; and the January and March 2027 cancellation windows.
How we did this
We included every S-1 compute agreement with a fixed amount or ceiling in the filing: Google, Amazon, Microsoft, SpaceXAI, Nscale, Lambda and Broadcom. We left out AMD's agreement, which states no fixed amount, and the $125 billion to $150 billion TPU estimate, which the S-1 keeps outside its table. Backlog figures are each supplier's own measure at its latest quarter end and are not defined the same way. Customer B's revenue is SpaceX's third-quarter revenue of $14.58 billion times 34.5%. Our code and inputs are saved with this piece.
