Anthropic is the unnamed "Customer B" that paid more than a third of SpaceX's revenue last quarter, Bloomberg reported on October 29, citing a person familiar with the matter. Bloomberg says Anthropic declined to comment, and a SpaceX spokesperson did not reply to its request for comment. Neither company has confirmed the match on the record.
The report puts a name on the biggest line in SpaceX's Form 10-Q for the quarter ended September 30, which SpaceX filed with the SEC on October 22. It also shows how much of SpaceX's new AI business rests on one AI lab.
What the filing says
SpaceX's 10-Q lists every customer above 10% of revenue in a note on concentration of risk, without naming them. There are two:
- Customer B: 34.5% of consolidated revenue in the third quarter of 2026 and 24.2% for the first nine months. It was below the 10% line in the same periods of 2025. The filing says its revenue "relates to the SI segment."
- Customer A: 16.6% of third-quarter revenue, down from 23.9% a year earlier, and 17.3% for the first nine months. Its revenue relates to all three of SpaceX's segments.
SpaceX reported total third-quarter revenue of $14.575 billion, up from $5.576 billion a year earlier. By our math, 34.5% of that is about $5.0 billion from Customer B in one quarter. The filing also says one customer held 27.7% of SpaceX's accounts receivable on September 30. At the end of 2025, no customer held 10% or more.
SI stands for Super Intelligence, the segment that used to be called AI. The 10-Q describes it as SI infrastructure for enterprise customers plus the Grok model, the Cursor coding platform and X. The segment brought in $7.56 billion in the quarter. Of that, $7.022 billion came from the "SI Solutions & Infrastructure" line, up from $359 million a year earlier. The filing says the SI segment began selling cloud services in 2026, priced as fixed monthly fees for "continuous access to reserved compute capacity."
How the Anthropic deal grew
The compute deal itself was public before today. When SpaceX filed for its IPO in May, it said Anthropic had agreed to pay $1.25 billion per month through May 2029, with lower fees during the May and June ramp-up, and that either side could end the deal with 90 days' notice.
The figures have grown since then. Anthropic's IPO prospectus, filed October 26, says Anthropic agreed to spend up to $120.5 billion with SpaceXAI over terms extending into 2029. That is about $3.1 billion a month once all capacity is delivered, which Anthropic expects in December 2026, with different fees while capacity ramps up. After initial non-cancelable periods ending in January 2027 and March 2027, either party can cancel each agreement on 90 days' notice. The prospectus also lists compute arrangements with Nscale, Lambda and other cloud providers. We covered other parts of that prospectus in our look at Anthropic's S-1.
The length of the deal has been disputed before. In May, Musk wrote on X, as quoted by TechCrunch: "This is a 180 day lease with 90 day notice mutual cancellation thereafter. The short term was our request, not Anthropic's." TechCrunch noted that SpaceX's S-1 described the customer as having "agreed to pay a monthly fee through May 2029."
Anthropic passes the US government
According to Bloomberg, revenue from Anthropic has surpassed payments from the US federal government, previously SpaceX's biggest single customer. Bloomberg says the other large customer in the filing "could be the aggregate of the government agencies it works with." The 10-Q itself does not say who Customer A is.
Bloomberg says the compute comes from SpaceX's data centers in Memphis, Tennessee, and that Musk has been turning SpaceX's AI business into a neocloud, a company that leases data center capacity to clients such as Anthropic and Alphabet's Google. Bloomberg reports that the AI business turned a profit for the first time this quarter. The 10-Q shows $431 million of income from operations for the SI segment in the third quarter. It also says the business has made SpaceX dependent on a single client while Wall Street turns against neoclouds. We covered the sector this week in reports on Fluidstack's fundraising and CoreWeave and Nebius shares.
Bloomberg says Musk, SpaceX's CEO, has argued that SpaceX is different from other neoclouds because it also earns money from Starlink and launches. In an October 25 post on X, quoted by CNBC, he wrote: "As of the past few weeks, debt markets have almost entirely shut off access to money for any company that doesn't have substantial revenue independent of AI data centers. That means the 200+ neoclouds are going to see guppy-level death and consolidation. Some will make it through, but not many."
What analysts are watching
At least one analyst has flagged concentration. After Anthropic's prospectus came out, Evercore ISI analyst Kutgun Maral calculated that $3.1 billion a month would be about $9.3 billion a quarter, or about 25% to 28% of SpaceX's $33 billion to $37 billion revenue guidance for the first quarter of 2027, Yahoo Finance reported. Maral said: "We do not see it as a near-term revenue risk given Anthropic's compute constraints and $131.7 billion of liquidity, but it does raise the question of how dependent SpaceX is on a single tenant."
If Bloomberg's report is right, SpaceX's largest source of revenue is now a set of contracts that either side can cancel on 90 days' notice after early 2027. The next 10-Q will show whether Customer B's share keeps rising, and Anthropic expects full capacity, at about $3.1 billion a month, in December.
Sources
- Bloomberg News (via Bloomberg Law): SpaceX's Largest, $3 Billion-a-Month "Customer B" Is Anthropic
- SpaceX Form 10-Q for the quarter ended September 30, 2026 (SEC EDGAR)
- Anthropic Form S-1 registration statement, filed October 26, 2026 (SEC EDGAR)
- Axios: Anthropic is paying SpaceX $15 billion per year
- TechCrunch: How long is Anthropic's lease with SpaceX? Opinions vary
- Yahoo Finance: SpaceX has a lot riding on the success of Anthropic
- CNBC: Elon Musk says more than 200 neoclouds face "guppy-level death"
