One AI Customer Made Up 34.5% of SpaceX’s Q3 Revenue

A single customer of SpaceX’s artificial intelligence business accounted for 34.5% of the company’s total revenue in the third quarter. That is according to SpaceX’s quarterly report on Form 10-Q, filed with the SEC on 22 October 2026. The filing calls it “Customer B” and says its revenue “relates to the SI segment”, SpaceX’s Super Intelligence unit. A year earlier, the same customer did not reach 10% of revenue.

In plain words: about $5.0 billion of SpaceX’s $14.6 billion of quarterly sales came from one AI customer, by our arithmetic (34.5% of $14,575 million), which is about two-thirds of the $7,560 million the SI segment booked. The filing does not name the customer.

Short explainer · SpaceX AI customer brief

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What happened next (28 Oct): the AI segment’s other figures from the same 10-Q, plus open roles on xAI’s careers board from our jobs tracker, are in SpaceX’s AI unit took 84% of capex as its sales rose 9.3x.

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Update, 29 October: Bloomberg Names Anthropic as Customer B

Anthropic is SpaceX’s largest customer, accounting for more than a third of its revenue in the third quarter, Bloomberg reported on 29 October, citing a person familiar with the matter (as relayed by The Next Web and Seeking Alpha; we read only Bloomberg’s headline). That would make Anthropic the “Customer B” in the 10-Q. Anthropic declined to comment and SpaceX did not respond, Bloomberg said. The identification is Bloomberg’s; the 10-Q itself still does not name the customer.

Against the filings, by our arithmetic: 34.5% of $14,575 million is about $5.03 billion for the quarter, or about $1.68 billion a month, above the $1.25 billion a month in the May agreements described in SpaceX’s S-1 ($3.75 billion a quarter). Seeking Alpha, citing Bloomberg, says monthly payments could reach about $3.1 billion beginning in December, and The Next Web says Anthropic could spend up to $120.5 billion on SpaceX computing through 2029 but can cancel after early 2027. The filings we read do not explain the gap between the quarter’s implied billing and the S-1 monthly fee.

What the Filing Shows

• Customer concentration. Customer B was 34.5% of consolidated revenue in the three months to 30 September 2026 and 24.2% over nine months; it did not exceed 10% in either 2025 period. A second customer, Customer A, was 16.6% of quarterly revenue and relates to all three segments.
• SI revenue. The segment’s revenue was $7,560 million, against $813 million a year earlier, up 829.9% (9.3 times, by our arithmetic). SI solutions and infrastructure revenue was $7,022 million, against $359 million.
• Why it rose. SpaceX attributes the increase mainly to “an increase in revenue from offering cloud services to customers for the full period and signing additional contracts during the period”, plus $608 million of revenue from Cursor after its acquisition in mid-August 2026 and higher Grok and X subscription revenue.
• Capacity. Nameplate compute was 1.7 gigawatts at 30 September 2026, against 0.6 gigawatts a year earlier, by SpaceX’s own definition (installed GPUs times their all-in power).

What Was Posted on X

Shay Boloor on X, 29 Oct: SpaceX spent 84% of its Q3 capex on AI while Starlink still generated 85% of operating profit; he notes AI already brings in more revenue than connectivity.

Andrew Curran on X, 29 Oct: Anthropic is SpaceX’s largest single customer, overtaking NASA and the Pentagon for the first time; 34.5% of SpaceX’s revenue last quarter came from compute-as-a-service to Anthropic, which has committed to spending up to $120.5 billion through 2029, with $3.1 billion a month starting in December 2026.

The AI Unit’s Profit Is Not the $4.4 Billion

SpaceX’s net income of $4,404 million for the quarter, against a net loss of $1,054 million a year earlier, is the figure for the whole company, not for the SI segment. In the segment table, SI’s income from operations was $431 million, against a loss of $1,722 million a year earlier.

The company-wide result also included $1,025 million of other income and a $390 million benefit from income taxes, according to the consolidated statement of operations. SI accounted for $16,444 million of SpaceX’s $19,593 million of quarterly capital expenditures, or 84%, by our arithmetic.

What SpaceX Disclosed Before

In its registration statement on Form S-1, filed on 20 May 2026, SpaceX named one cloud customer: “in May 2026, we entered into Cloud Services Agreements with Anthropic PBC”, under which “the customer has agreed to pay us $1.25 billion per month through May 2029, with capacity ramping in May and June 2026 at a reduced fee.” The S-1 adds that the agreements “may be terminated by either party upon 90 days’ notice.”

At $1.25 billion a month, a full quarter comes to $3.75 billion, by our arithmetic. The 10-Q does not say who Customer B is, and we did not identify it from the filing; Bloomberg has since reported that it is Anthropic (see the 29 October update above).

Connecting the Coverage

SpaceX’s headline third-quarter numbers, including the $7.56 billion of SI revenue, came out on 20 October, as we reported then. The company said it was on track to add 200,000 Nvidia Blackwell GPUs a month, as we reported on 20 October, and its $40 billion GPU deal is a five-year finance lease arranged with Apollo, as we reported on 26 October. The $1.25 billion monthly figure in the S-1 gives no total, as our 28 October correction notes, and buyers of AI compute are spreading their bets, with OpenAI planning to buy Google’s TPUs, as The Information reported and we covered on 28 October. What’s new here: the 10-Q shows how concentrated SpaceX’s AI revenue has become.

The Structural Read

SpaceX’s 10-Q attributes the SI increase mainly to cloud services for the full period and new contracts, plus $608 million from Cursor after its mid-August acquisition.

As we read it, the company-wide net income of $4,404 million overstates what the AI unit earns: the segment table shows SI income from operations of $431 million.

SpaceX’s S-1 says its agreements with Anthropic can be terminated by either party on 90 days’ notice; the 10-Q does not say who Customer B is.

Three Implications

FOR SPACEX INVESTORS The 10-Q shows one customer at 34.5% of quarterly revenue; it was under 10% of revenue in both 2025 periods.

FOR AI COMPUTE BUYERS SpaceX’s S-1 describes $1.25 billion a month for access to compute capacity in the Anthropic agreements, at a reduced fee during the May-June 2026 ramp, terminable by either party on 90 days’ notice.

FOR READING THE HEADLINE PROFIT Net income of $4,404 million is company-wide and includes $1,025 million of other income and a $390 million tax benefit, the 10-Q shows.

The Business Engineer Lens

This story maps onto the Business Engineer framework The AI Capex Map.

The framework argues that “The $1T capex cycle is being underwritten by a $1T concentrated demand commitment from two counterparties whose combined free cash flow is deeply negative”.

As we read it, SpaceX’s 10-Q shows the same pattern on the seller’s side: one SI-segment customer accounted for 34.5% of quarterly revenue. The framework was published in May 2026 and does not discuss SpaceX’s 10-Q or Customer B.

What Is Not Established

The 10-Q does not name Customer B (Bloomberg’s identification of Anthropic rests on a person familiar with the matter), and its quarterly revenue from that customer is our arithmetic from the 34.5% share. The S-1 describes the Anthropic agreements, including the ramp at a reduced fee, but gives no total and does not say how much was billed in the third quarter. We did not contact SpaceX or Anthropic.

The Bottom Line

SpaceX’s 10-Q shows one SI-segment customer at 34.5% of third-quarter revenue, about $5.0 billion by our arithmetic, as the AI unit’s sales rose to $7,560 million from $813 million. The $4,404 million net income is company-wide; the SI segment’s income from operations was $431 million.