SpaceX · AI · 29 Oct 2026
Anthropic's IPO filing puts its SpaceX compute bill at $3.1 billion a month, 2.5 times what SpaceX disclosed in June
Anthropic's preliminary IPO prospectus says it has agreed to spend up to $120.5 billion with SpaceXAI for Nvidia GPU compute, about $3.1 billion a month once all capacity is delivered (S-1, as of 26 Oct 2026). That's about $9.3 billion a quarter at full rate, more than SpaceX's whole Super Intelligence segment brought in last quarter. It's also the only one of Anthropic's big compute deals that either side can walk away from on 90 days' notice.
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The editor holds Tesla and SpaceX shares. Supercharged Daily is independent and not affiliated with either company. Nothing here is financial advice.
What the filing says
Anthropic filed its Form S-1 with the SEC on Monday, 26 Oct 2026. EDGAR shows it accepted at 9:00am ET (6:00am PT; ). An S-1 is the registration statement a company files before it goes public. Anthropic says it has applied to list on the Nasdaq Global Select Market under the symbol "ANT", but the price range is still blank and no amended S-1 or final prospectus had been filed as of 29 Oct 2026. The IPO isn't priced.
In its section on contractual obligations, the S-1 says that "between May and October 2026, we entered into and amended several agreements with SpaceX.AI LLC (formerly known as X.AI LLC)," which it calls "a wholly owned subsidiary of Space Exploration Technologies Corp." The terms:
- Size: Anthropic "agreed to spend an aggregate of up to $120.5 billion over terms extending into 2029." That's a ceiling, not a guaranteed amount.
- Monthly rate: "approximately $3.1 billion in the aggregate per month once all capacity has been delivered, which we expect in December 2026, with different fees during capacity ramping periods." December is Anthropic's expectation, not a done deal.
- Hardware: compute "powered by NVIDIA GPUs." The S-1 doesn't name a data center.
- Exit terms: "Following initial non-cancelable periods ending in January 2027 and March 2027 under the respective agreements, each agreement may be cancelled by either party upon 90 days' advance written notice."
How the deal grew since May
The partnership has been public since 6 May 2026. Anthropic announced it in a blog post that also raised Claude usage limits, saying it would use "all of the compute capacity" at SpaceX's Colossus 1 data center, "over 220,000 NVIDIA GPUs." SpaceX's AI arm posted its own announcement. The same day, Anthropic co-founder Tom Brown posted that Claude inference was moving onto Colossus:
In the next few days we'll be ramping up Claude inference on Colossus.
— Tom Brown (@NotTomBrown) May 6, 2026
Grateful to be partnering with SpaceX here. We are going to need to move a lot of atoms in order to keep up with AI demand, and there's nobody better at quickly moving atoms (on or off planet Earth)
Musk replied about half an hour later that he had "spent a lot of time last week with senior members of the Anthropic team" and "was impressed," and that he was then "ok leasing Colossus 1 to Anthropic."
SpaceX gave the first price in its final IPO prospectus, dated 11 June and filed on 12 June 2026. It said Anthropic had agreed to pay "$1.25 billion per month through May 2029" for compute across Colossus and Colossus II that "includes approximately 325,000 NVIDIA GPUs." The same prospectus dates the first cloud services agreement to 3 May 2026 and says that "after the initial three-month period, the agreements may be terminated by either party upon 90 days' notice."
| Term | SpaceX prospectus (June 2026) | Anthropic S-1 (26 Oct 2026) |
|---|---|---|
| Monthly fee | $1.25 billion | About $3.1 billion once all capacity is delivered |
| Total | Not stated | Up to $120.5 billion |
| Runs until | May 2029 | "Into 2029" |
| Locked-in period | First three months | Until January 2027 and March 2027 |
| Notice to cancel after that | 90 days, either party | 90 days, either party |
$3.1 billion divided by $1.25 billion is 2.48, so the monthly rate is about 2.5 times what SpaceX disclosed in June, and the locked-in periods are longer. The S-1 says the agreements were "amended" between May and October but doesn't say how much extra capacity came with the higher fee. Neither filing says which data centers the added capacity comes from.
How big $3.1 billion a month is for SpaceX
These figures are my own math, using SpaceX's third-quarter 10-Q (filed 22 Oct 2026):
- $3.1 billion a month is about $9.3 billion a quarter. SpaceX's Super Intelligence (SI) segment, which includes Grok, X, Cursor and the compute it rents out, had $7.56 billion of revenue in the third quarter. At full rate, this one contract would be about 23% bigger than that whole segment was last quarter.
- It's also about 64% of SpaceX's total third-quarter revenue of $14.58 billion.
- Over a year, it comes to about $37.2 billion, against about $15 billion a year at June's $1.25 billion rate.
- $120.5 billion divided by $3.1 billion is about 39 months of full-rate payments.
It's a big bill for Anthropic too. Its S-1 shows $16.29 billion of revenue in the first half of 2026 and $8.95 billion of compute and infrastructure expenses. Six months at the full SpaceXAI rate would be about $18.6 billion, roughly double what Anthropic spent on compute and infrastructure in the first half.
Is Anthropic SpaceX's "Customer B"?
On 24 Oct we looked at SpaceX's 10-Q. It shows that one unnamed customer, "Customer B," accounted for 34.5% of SpaceX's third-quarter revenue, all of it in the SI segment. That's about $5.0 billion, or roughly $1.7 billion a month.
The new filing fits that number. $1.7 billion a month is above June's $1.25 billion rate and below the $3.1 billion full rate Anthropic expects in December, which is what you'd see from a contract that's still ramping up. The 10-Q also describes cloud services with "a fixed monthly services fee" over a contract term "typically three years and terminable by either party upon 90 days' notice." Those match the terms Anthropic describes.
Neither company has said Anthropic is Customer B, and SpaceX doesn't name it. The numbers point that way, but that's my inference. Nothing in either filing confirms it.
The biggest compute deal, and the easiest to cancel
The S-1 describes Anthropic's other big compute service deals in the same section, and the terms differ a lot from one provider to the next:
| Provider | Amount | Period | Can Anthropic walk away? |
|---|---|---|---|
| SpaceXAI | Up to $120.5B | Into 2029 | Yes. Either side, 90 days' notice, after Jan/Mar 2027 |
| At least ~$114.5B | Apr 2026 – Jul 2033 | No. Pays "regardless of actual usage" | |
| Amazon | At least $110.0B | May 2026 – Apr 2036 | No. Pays "regardless of actual usage" |
| Microsoft | At least $44.9B | Nov 2026 – May 2033 | No. Pays "regardless of actual usage," except for undelivered tranches |
| Nscale | Up to ~$44.6B | Into 2033 | Mostly no. Fees accrue only as capacity is delivered and accepted |
| Lambda | About $41.3B | Into 2034 | Mostly no. Fees accrue only as capacity is delivered and accepted |
Source for every row: Anthropic's S-1. Anthropic also estimates $125 billion to $150 billion for extra TPU compute from providers including Google, delivered between 2028 and 2031, and expects more than $20 billion under an AMD deal. Neither is in its commitments table. Separately, its Broadcom equipment leases add up to about $161.2 billion in rent.
SpaceXAI has the largest figure of the compute service deals the S-1 describes, but it's an "up to" ceiling, while the Google, Amazon and Microsoft figures are minimums. Anthropic has to pay those three "regardless of actual usage," and if its spending with Google or Amazon falls short, it "must pay" them "the difference as a true-up." The SpaceXAI agreements have a 90-day exit for either party once the locked-in periods end early next year. That cuts both ways, so SpaceX could take the capacity back too. Its own June prospectus lists "prioritization of internal versus external compute usage" among the risks of its AI strategy.
What's confirmed and what isn't
- Confirmed in filings: the agreements exist, were entered into or amended between May and October 2026, and run up to $120.5 billion at about $3.1 billion a month at full capacity (Anthropic S-1). The original deal was priced at $1.25 billion a month (SpaceX prospectus).
- Expected, not delivered: full capacity in December 2026. That's Anthropic's own projection.
- A ceiling, not a guarantee: the $120.5 billion is "up to." Either side can cancel on 90 days' notice once the January and March 2027 lock-ins pass.
- Not confirmed: that Anthropic is SpaceX's Customer B, and which data centers the added capacity comes from.
- Still pending: Anthropic's IPO. The S-1 is a preliminary registration statement, and the shares haven't been priced.
My read
When SpaceX went public in June, its prospectus described the Anthropic deal as "monetization of unused compute capacity," at $1.25 billion a month. At full rate, Anthropic now expects to pay about $9.3 billion a quarter. That's more than SpaceX's whole SI segment made last quarter and close to two-thirds of the company's total quarterly revenue. It's very good for SpaceX's revenue line, but it also concentrates a lot of that revenue in a contract that becomes cancelable early next year. Two things to watch: SpaceX's next quarterly report, where Customer B's share should show whether the $3.1 billion rate arrived in December, and any amended S-1 from Anthropic before it prices, which could change these terms again.
Sources: Anthropic, PBC, Form S-1 (filed 26 Oct 2026) and its EDGAR filing index; Space Exploration Technologies Corp., final prospectus (424B4, filed 12 Jun 2026); SpaceX Form 10-Q for the quarter ended 30 Sep 2026 (filed 22 Oct 2026); Anthropic, "Higher usage limits for Claude and a compute deal with SpaceX" (6 May 2026); "New Compute Partnership with Anthropic" (x.ai); @NotTomBrown and @elonmusk on X (6 May 2026).
— Alex R
