SpaceX's largest customer is Anthropic, Bloomberg reported on Thursday. The relationship between them has been amended since SpaceX last described it by name, and the amendment is on file at one of the two companies. This bridge sets the two records side by side ahead of next week's ledger.
What SpaceX told the Staff
On Thursday, May 28, Elon Musk described the arrangement on X as a 180-day lease with a mutual 90-day notice period, and wrote, "The short term was our request, not Anthropic's." (1)
The next day the SEC's staff asked SpaceX what consideration it had given to filing its Anthropic agreements as exhibits. SpaceX answered through counsel on June 1. The agreements, it wrote, were entered into in the ordinary course of its business and fall in none of the four categories of ordinary-course contracts that Item 601(b)(10)(ii) of Regulation S-K requires a registrant to file. (2)
The second category carries the weight: contracts "upon which the Company's business is substantially dependent." SpaceX gave two reasons the Anthropic agreements sit outside it. If they ended, the capacity "would easily be redeployed to other customers given the shortage of frontier AI compute capacity," or used for its own models. And either party may terminate on 90 days' notice, a right "which either party may exercise without adverse contractual consequences," and which SpaceX called "inconsistent with the substantial dependence requirement." The flexibility, it added, is "a reason why the Company negotiated for a termination provision." (2)
The position rests on the exit clause, and SpaceX asked for the short term. Ordinary course places the agreements outside the exhibit rule, the 90 days keep them clear of the one exception that would bring them back in, and Musk had said four days earlier that the short term was SpaceX's request.
The terms in June
Anthropic announced the arrangement first, on May 6, on its own website: "all of the compute capacity at their Colossus 1 data center," "more than 300 megawatts of new capacity" and "over 220,000 NVIDIA GPUs," with no price, term or exit. (3)
The final prospectus of June 12 gave the terms. Anthropic would pay $1.25 billion a month through May 2029 for compute across Colossus and Colossus II, about 325,000 NVIDIA GPUs, with capacity ramping in May and June at a reduced fee. "After the initial three-month period, the agreements may be terminated by either party upon 90 days' notice." At the full rate, thirty-five to thirty-seven months comes to $43.75 billion to $46.25 billion. Between the announcement and the prospectus, the described capacity grew from Colossus 1 to Colossus and Colossus II, and from over 220,000 GPUs to about 325,000 (OURS, on the two descriptions). (3)
The terms in October, from the buyer
Anthropic's registration statement of October 26 describes the relationship from the other side: "Between May and October 2026, we entered into and amended several agreements with SpaceX.AI LLC." Anthropic agreed to spend up to $120.5 billion over terms extending into 2029, about $3.1 billion a month once all capacity is delivered, which it expects in December. "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." (4)
Three things moved between June and October. The monthly rate at full delivery is 2.48 times the June rate. The total is up to $120.5 billion, against $43.75 billion to $46.25 billion. And the stretch before either side may give notice now runs to January and March 2027, where the June terms put it three months in. The 90-day clause survives, with more months in front of it. (4)
The S-1 ties its two October figures together, and on their own arithmetic a fourth thing may have moved. The S-1 gives "up to" $120.5 billion, "consisting of approximately $3.1 billion in the aggregate per month" from December, after ramp months at fees it leaves unstated, over terms "extending into 2029." With the ramp priced anywhere from the June rate to the full one, the total is reached in the second half of 2029, between late July and early December. For the terms to end in May 2029, as June's did, between $5.80 billion and $18.75 billion of the total would go unspent. The one filed description of the ramp, a "reduced fee" for May and June, points to the later end. Either the end month moved later in 2029, or "up to" carries that much room. The filing allows both. Its obligations table, which runs by year and is blank in the October filing, is the first place the answer could print. (4)
SpaceX's record since
On August 4 SpaceX's second-quarter report added a risk factor: "Our cloud services agreements generally provide for monthly fees and, after an initial period inclusive of capacity ramp (generally, a number of months), may be terminated by either party upon 90 days' notice." Customer B supplied 19.5 percent of second-quarter revenue. The June description named Anthropic and three months. The August one names neither, and its "number of months" holds either length. (5)
SpaceX filed its third-quarter report on October 22, stating no material change to that risk factor. Customer B supplied 34.5 percent of revenue of $14,575 million, about $5.03 billion, or about $1.68 billion a month, and 24.2 percent of nine-month revenue. One customer held 27.7 percent of receivables. The report names Anthropic zero times, and its revenue policy describes cloud services contracts as "typically three years and terminable by either party upon 90 days' notice." (5)
SpaceX has filed ten current reports since the prospectus. Item 1.01 appears in one of them, for the Cursor merger agreement. No SpaceX filing since the prospectus names Anthropic. (6)
On October 29 Bloomberg reported that Customer B is Anthropic. (7) The report aligns the two records. About $1.68 billion a month sits between the June rate and the October one, the shape of a ramp, as our first read of the S-1 found on October 26. (8)
The report supplies the link the filings leave unmade. It fits, and the arithmetic supports it, but a report joining two filings is a different thing from two filings describing one relationship. Part of what the two records show rests on that connection, which is sound and short of certain. The gap between them has its explanation in SpaceX's own terms: ordinary course, and an exit that keeps the agreements outside the exhibit rule.
Everything filed about the amendment is at Anthropic. SpaceX's own filings carry the customer as a letter and a percentage, and the terms in general words.
The fourth deal
On September 10 SpaceX's chief financial officer told a Goldman Sachs conference that SpaceX had closed a fourth hosting agreement in early September, at about $1.11 billion a month from December 1, and named no counterparty. (9)
Anthropic's filing places "several agreements," some entered into and some amended, between May and October, with full delivery expected in December. The CFO's deal falls inside that window and starts the same month. Whether it is an addition to the Anthropic relationship, a supplement to it, or a different customer altogether, neither company's filings say. The arithmetic leaves room either way: $1.25 billion and $1.11 billion together come to $2.36 billion a month, short of Anthropic's $3.1 billion. (9)
The question for the ledger is whether this is one relationship or two, and the CFO's remarks are the one place the answer was spoken without being filed.
The line, and the ground in front of it
SpaceX's June position may hold as the agreements now stand. The 90-day clause is still in them, and the judgment under Item 601 belongs to SpaceX and the Staff. (2)
What moved is the ground in front of the line. The argument was made for a customer paying $1.25 billion a month and free to give notice three months in, on a short term SpaceX itself had asked for. SpaceX's general wording since August, "a number of months," covers what followed. On the buyer's filing, that customer now has terms of about $3.1 billion a month at full delivery and no notice before early 2027, and it was a third of SpaceX's third-quarter revenue, more than twice the 16.6 percent of Customer A, the next largest, in the same quarter. With Customer B at the full rate and every other line flat, it would be about 49 percent of a quarter's revenue. (10) A position built on the exit clause now covers SpaceX's largest customer by a wide margin.
Amazon shows the other way to record it. Its third-quarter report states, "We also amended our commercial arrangement" with Anthropic, and ties a $20 billion financing facility to "certain delivery milestones of compute capacity under the amended commercial arrangement." (11) Both companies are inside the rules. Amazon describes the amendment on its own record, and SpaceX's last description sits in a June prospectus.
What settles it
SpaceX's 10-K, early in 2027, carries Customer B's full-year share. Anthropic's S-1/A carries its contractual obligations by year, which will date the $120.5 billion. The first exits fall between January and June 2027, depending on when notice may be given. Under SpaceX's ordinary-course position, a termination may arrive as a concentration line in a periodic report, and that is where next week's ledger begins. (12)
Free to read, no paywall. Readers who find the work useful can support it at the foot of the page; payment offsets the time and buys no access. Corrections run in daylight, dated, in a comment or in the following piece, and a reader who finds one is doing us a favor.
Standing Disclosure
Cape Fear Advisors holds no direct position, long or short, in the securities discussed here. Any exposure is indirect, through managed funds it does not control, which may include index funds holding the public companies named.
Notes
[1] REPORTED. Posts on X by Elon Musk on Thursday, May 28, 2026, as reported by Yahoo Finance (Fiona Craig, June 1, 2026), which quotes: "SpaceX has not committed to leasing Colossus for years, although it's possible that may be what happens"; "The short term was our request, not Anthropic's"; and "We won't leave them hanging and will provide a reasonable off-ramp," and describes the terms as a 180-day lease followed by a mutual 90-day cancellation notice. The posts were not read at source. The 180 days in the posts and the "initial three-month period" in the prospectus of note (3) are carried as stated.
[2] FILED. SpaceX correspondence of June 1, 2026, accession 0001628280-26-039278, from Gibson, Dunn & Crutcher LLP for the Company, responding to comment 1 of the Staff's letter of May 29, 2026 on the Registration Statement filed May 20 (File No. 333-296070); read at source October 30, 2026. The Staff's comment, as restated in the letter, asks the Company to "tell us what consideration" it gave "to filing this agreement," citing Item 601(b)(10) of Regulation S-K. The four categories are Item 601(b)(10)(ii)(A) to (D). SpaceX's next response, June 3, 2026 (accession 0001628280-26-040379), names Anthropic zero times and cites Item 601 zero times; the June 9 letters (0001628280-26-041806 and -041808) are acceleration requests. The Staff's letter of June 2 is a PDF upload not read for this piece. The reading of which reason carries the position is ours. No legal conclusion is drawn.
[3] Company release, not filed with the Commission: Anthropic, "Higher usage limits and a SpaceX compute deal," anthropic.com/news, May 6, 2026, read October 31, 2026: "We've signed an agreement with SpaceX to use all of the compute capacity at their Colossus 1 data center. This gives us access to more than 300 megawatts of new capacity (over 220,000 NVIDIA GPUs) within the month." It states no price, term or termination provision, and adds that Anthropic has "expressed interest in partnering with SpaceX to develop multiple gigawatts of orbital AI compute capacity." FILED. SpaceX final prospectus, Form 424B4, accession 0001628280-26-042639, June 12, 2026, Business ("Compute capacity provided includes approximately 325,000 NVIDIA GPUs"; "$1.25 billion per month through May 2029, with capacity ramping in May and June 2026 at a reduced fee. After the initial three-month period, the agreements may be terminated by either party upon 90 days' notice"). The subsequent-events note to the financial statements (page F-63) describes one agreement of May 3, 2026, terminable "by either party upon 90 days' notice," and states no initial period. OURS: 35 x $1.25 billion is $43.75 billion; 37 x $1.25 billion is $46.25 billion; the reduced ramp fee is unquantified, so the term total sits in that band, as in our September 30 piece.
[4] FILED. Anthropic, PBC, Form S-1, accession 0001628280-26-067168, October 26, 2026, Management's Discussion and Analysis, the commitments following the contractual commitments table (page 172), read at source October 30, 2026: "we agreed to spend an aggregate of up to $120.5 billion over terms extending into 2029, consisting of 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." The counterparty is "SpaceX.AI LLC (formerly known as X.AI LLC) ('SpaceXAI'), a wholly owned subsidiary of Space Exploration Technologies Corp."; SpaceX's financial statements are consolidated, and its concentration disclosure covers its subsidiaries' customers. OURS, an illustration on stated assumptions: ramp from May through November 2026, seven months, at a rate r between the June $1.25 billion and the full $3.1 billion; full rate from December 2026. The total 7r + 3.1m = $120.5 billion gives m of 36.05 months at r = 1.25 (reached at the start of December 2029, December 2026 being month one) and 31.87 months at r = 3.1 (reached late in July 2029). With a May 2029 end, the full-rate months are 30 ($93.0 billion), and the unspent remainder is $27.5 billion less 7r: $18.75 billion at r = 1.25 (15.6 percent of the total) and $5.8 billion at r = 3.1. A May 2029 end with the whole total spent would need r of $3.93 billion, above the full rate. Dividing $120.5 billion by $3.1 billion without the ramp gives 38.9 months and is not used. If Customer B is Anthropic (REPORTED, note 7), SpaceX's filed shares put Customer B revenue at about $6.55 billion for May through September (24.2 percent of $27,083 million nine-month revenue), which, with October and November 2026 held anywhere from the May-to-September average to the full rate, narrows the implied end to October or November 2029. The same figures put May and June at about $763 million a month ($6,554 million less the third quarter's $5,028 million, over two months), below the $1.25 billion contract rate and consistent with the filed reduced ramp fee, and July to September at about $1,676 million a month. That narrowing rests on the reported link and on SpaceX's revenue timing. The obligations table on page 170, with columns 2026 to 2030 and thereafter, is blank in the October 26 filing; its notes state it carries minimum payments under non-cancelable commitments. The Exhibit Index lists no SpaceXAI agreement; the compute-related exhibits are 10.11 (Master Equipment Lease Agreement with Broadcom) and 4.3 to 4.5 (note facilities with Amazon Web Services, Broadcom and Google). OURS: $3.1 billion over $1.25 billion is 2.48.
[5] FILED. SpaceX Form 10-Q for the quarter ended September 30, 2026, accession 0001628280-26-066880, Part II, Item 1A, incorporating the risk factors of the second-quarter report and stating "no material changes," concentration of risk (Customer A 16.6 percent and Customer B 34.5 percent of third-quarter revenue; Customer B 24.2 percent of nine-month revenue of $27,083 million, its revenue in the SI segment; one customer 27.7 percent of accounts receivable, net) and the SI revenue policy. Text search October 30, 2026: "Anthropic" 0. OURS: 34.5 percent of $14,575 million is $5,028 million; a third of that is $1,676 million. FILED: SpaceX Form 10-Q for the quarter ended June 30, 2026, accession 0001628280-26-052535, Part II, Item 1A (the risk factor quoted, supplementing the prospectus) and concentration of risk (Customer A 18.3 percent and Customer B 19.5 percent of second-quarter revenue; Customer B's revenue in the AI segment). Text search October 30, 2026: "Anthropic" 0.
[6] FILED probe. EDGAR submissions for Space Exploration Technologies Corp. (CIK 1181412), read at 19:23 UTC October 30, 2026: Forms 8-K of June 15, 16, 17, 22, 23 and 26, August 4 and 14, and October 20 and 26. Item 1.01 appears on June 16 only, Exhibit 10.1, the Agreement and Plan of Merger with Anysphere, Inc. (Cursor). The October 26 report, Item 8.01, concerns the Apollo GPU finance lease. The full submissions list since June 12, re-read at 21:03 UTC October 30, 2026, carries ten Forms 8-K, two Forms 10-Q, three Forms S-8 and ownership filings (Forms 3, 4, 4/A and 144, and four Schedules 13G). Every 8-K, 10-Q and S-8 was text-searched: "Anthropic" 0 in each. The ownership filings carry no narrative text about the Company's agreements and were not opened. The two 10-Qs describe cloud services agreements in the general terms quoted in the body. Re-run at 13:23 UTC October 31, 2026: no new filing on the SpaceX or Anthropic, PBC (CIK 2130357) dockets; Anthropic's latest remains the S-1 of October 26. Re-run at 13:39 UTC October 31, 2026: unchanged. Re-run at 13:49 UTC October 31, 2026: unchanged. Re-run at 14:02 UTC October 31, 2026: unchanged.
[7] REPORTED. Dina Bass, Carmen Arroyo and Loren Grush, Bloomberg, October 29, 2026, citing a person familiar with the matter.
[8] OURS on FILED. Cape Fear Advisors, "Anthropic, First Read," October 26, 2026.
[9] REPORTED. Remarks by SpaceX's chief financial officer at the Goldman Sachs Communacopia and Technology Conference, September 10, 2026, as carried in coverage that day (Cybernews; Pulse2). The remarks were not read at source: a fourth hosting agreement, closed in early September, at about $1.11 billion a month from December 1, 2026, about $13 billion a year, counterparty unnamed. No filing read for this piece describes it, and the Q3 10-Q exhibit index carries certifications only. OURS: $1.25 billion plus $1.11 billion is $2.36 billion.
[10] OURS, an illustration. At the full rate, $3.1 billion x 3 is $9.3 billion a quarter. Third-quarter revenue less Customer B is $14,575 million less $5,028 million, $9,547 million. $9,300 million over $18,847 million is 49.34 percent, printed floored. All other revenue is held at the third quarter's level, and the figure is an illustration.
[11] FILED. Amazon.com, Inc. Form 10-Q for the quarter ended September 30, 2026, accession 0001018724-26-000040, the note on Anthropic investments, read at source October 30, 2026: "We also amended our commercial arrangement primarily for the provision of AWS cloud services, which includes contractual obligations related to the performance of AWS chips," and a facility "not to exceed $20.0 billion" made available "as we reach certain delivery milestones of compute capacity under the amended commercial arrangement."
[12] FILED terms per note (4). OURS: the window from the end of the first non-cancelable period to 90 days past the second.
Analysis: Cape Fear Advisors.
This piece also appears on Substack. Cape Fear Advisors is an independent advisory firm based in Portsmouth, NH.
Contact Cape Fear Advisors