Anthropic Said to Be a Third of SpaceX’s Revenue

STARBASE, Tex., Oct. 29 — AnthropicAnthropic is SpaceX’s largest single customer, the unnamed “Customer B” that accounted for 34.5 percent of SpaceX’s third-quarter revenue, Bloomberg News reported on Thursday, citing one person familiar with the matter. SpaceX’s quarterly report, filed on Oct. 22, does not name the customer; it says only that its revenue “relates to the SI segment,” where SpaceX books its cloud-computing sales.

By this paper’s arithmetic, that is about $5.0 billion, roughly two-thirds of the $7.56 billion SpaceX’s Super Intelligence segment took in, and more than the $3.12 billion Starlink’s consumer business brought in. A year earlier, Customer B accounted for no more than 10 percent, the filing says.

If the report is right, it puts a number on a dependence that runs both ways. SpaceX, which named Anthropic among its AI business’s key competitors in its June prospectus, would now be drawing more than a third of its revenue from it. For investors weighing Anthropic’s own listing, it suggests how much of the lab’s computing bill goes to a single supplier. Anthropic has not reported its third-quarter costs; in the second quarter, its entire compute and infrastructure expense was $5.6 billion, its prospectus says. The figures cover different quarters and different companies’ books.

SpaceX named Anthropic as a customer when it went public in June. Its prospectus said Anthropic had agreed in May to pay $1.25 billion a month through May 2029, with capacity “ramping in May and June 2026 at a reduced fee.”ColossusSpaceX’s June prospectus said the capacity spans Colossus and Colossus II, its data centers in Memphis and Southaven, Miss., and includes about 325,000 Nvidia GPUs. Anthropic’s prospectus, filed on Oct. 26, says it signed and amended several agreements with SpaceXAI, a SpaceX subsidiary, from May to October, under which Anthropic agreed to spend up to $120.5 billion over terms extending into 2029: about $3.1 billion a month once all the capacity is delivered, which it expects in December. This paper set out those terms on Oct. 27.

SpaceX’s figures trace the ramp. Over nine months, Customer B accounted for 24.2 percent of revenue, about $6.6 billion by this paper’s arithmetic, which leaves about $1.5 billion before July. The third quarter’s $5.0 billion works out to about $1.7 billion a month, above the fee in SpaceX’s June prospectus and below the rate Anthropic expects at full delivery.Fixed FeesSpaceX accounts for its cloud contracts as “a stand-ready promise to provide continuous access to reserved compute capacity,” for fixed monthly fees.

SpaceX’s report says its cloud contracts typically run three years and are “terminable by either party upon 90 days’ notice,” and Anthropic’s prospectus says either side may cancel its agreements that way once initial non-cancelable periods end in January and March 2027. The concentration shows in what SpaceX is owed, too. At Sept. 30, one customer accounted for 27.7 percent of its $4.77 billion of accounts receivable, about $1.3 billion by this paper’s arithmetic; at the end of 2025, no customer accounted for 10 percent. The filing does not say which customer. Customer A, also unnamed, whose revenue spans all three of SpaceX’s segments, accounted for 16.6 percent.

SpaceX has presented the short terms as a choice. On its Oct. 20 call, Elon Musk, the chief executive, said SpaceX preferred to rent at “effectively the spot market rate” rather than sign long deals, and that “we could rent out our compute several times over if we said yes to everyone,” according to a transcript published by The Motley Fool.

Anthropic, for its part, tells investors in its prospectus that it “can secure compute from multiple providers rather than being constrained by any single provider.” It also warns that some cloud providers it relies on offer AI models of their own, and that if they cut or fail to raise its allocations, it may have to seek compute elsewhere on less favorable terms and could be “unable to secure adequate alternative compute, or any at all.”

Kutgun Maral, an analyst at Evercore ISI, weighed the risk to SpaceX after Anthropic’s filing, as quoted by Yahoo Finance on Oct. 27: “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.” That figure matches the cash and short-term investments Anthropic reported at June 30.

Bloomberg’s report rests on one person, who, it said, declined to be identified because the details are private. Anthropic declined to comment, and SpaceX did not respond, Bloomberg said, according to The Next Web. SpaceX’s shares closed Thursday at $143.89, down 0.92 percent.

Amazon, another Anthropic supplier and investor, said on Thursday that its third-quarter net income fell from a year earlier mainly because the 2025 quarter had included $9.5 billion of pre-tax gains on its Anthropic investments.

What to watch: Anthropic’s amended prospectus, not yet filed; SpaceX’s fourth-quarter report, which should show whether Customer B’s share keeps rising as the capacity is fully delivered; and the cancellation windows that open in January and March 2027.

Daily Cortex is written with AI models, including Anthropic’s Claude, and fact-checked with OpenAI’s GPT models.