Anthropic SpaceX compute deal — $120.5 billion is a ceiling, with a 90-day exit from early 2027

Three different kinds of statement about the Anthropic and SpaceX compute contract circulated on November 11, 2026: a clause in a filing, an unconfirmed account of a private meeting, and one line from Elon Musk. The filing is the second amendment to Anthropic's S-1, submitted to the US Securities and Exchange Commission on Tuesday, November 10 (US time). It says Anthropic agreed to spend up to $120.5 billion through 2029 renting computing capacity from SpaceX's AI subsidiary. The same paragraph says the agreements can be cancelled on 90 days' notice from early 2027.

The unconfirmed account is a post on X from Wednesday, November 11, saying Anthropic told sell-side analysts it would not extend the contract beyond the middle of 2027. Neither Anthropic nor SpaceX has confirmed that. Musk wrote on X the same day: "We would be happy to take the compute back. No problem. But I think the opposite is going to happen." Only the clause is established. There is no report that either side has served notice.

1. What the filing says: a maximum, not a promise

The disclosure is a single paragraph. Between May and October 2026, Anthropic entered into and amended several agreements with SpaceX.AI LLC, formerly X.AI LLC and a wholly owned subsidiary of SpaceX, for compute powered by Nvidia GPUs. The filing calls them the SpaceXAI Arrangements.

The arithmetic is consistent: $3.1 billion a month is $9.3 billion a quarter and $37.2 billion a year. The $120.5 billion figure is what that rate adds up to if it runs uninterrupted into 2029, which is why the filing says "up to."

Turning the clause into dates changes the picture. If notice were served on the last day of each non-cancelable period, the agreements would end as follows.

The two companies are legally bound to each other only until roughly the second quarter of 2027. The "mid-2027" in the X post coincides with the earliest exit the clause allows. Whether or not the post is accurate, revenue after mid-2027 was never guaranteed. The filing does not say whether notice can be given before the initial periods end.

The deal grew several times in six months.

The monthly fee rose about 2.5 times, from $1.25 billion to $3.1 billion. Musk has said whose idea the short term was. On May 28 he wrote: "The short term was our request, not Anthropic's." He added that SpaceX would provide "a reasonable off-ramp" but might need the capacity back "if compute gets super tight." SpaceX wants the option to reclaim capacity for its own Grok models. Its quarterly report describes cloud-services contracts in general as typically three years long and terminable by either party on 90 days' notice.

2. What was said on November 11, and how much of it is confirmed

The trigger was a post by the X account @jukan05. TeslaNorth identifies the author as a semiconductor analyst at Citrini Research who regularly posts English summaries of sell-side notes and supply-chain research. The fact-checking write-up by CellCog timed the post at 11:46 UTC on November 11. It listed four remarks said to have been made by Anthropic to sell-side analysts.

About 41 minutes later the same account corrected the second item, saying the $10 billion reportedly covered the whole Claude 5.5 family rather than Opus 5.5 alone. The post did not name the meeting, the bank hosting it or the speaker, and no transcript or recording has surfaced. TeslaNorth noted there is no public record of how often the account's relayed notes prove accurate.

Readers split over what the remark meant. According to TeslaNorth, X user Aaron Burnett argued that people were reading too much into secondhand notes and that Anthropic may have been answering a hypothetical about weaker AI demand leaving it paying above-market rates. Musk's line was a reply to that post.

Musk did not say whether "the opposite" meant an extension, more capacity or stronger demand. He was responding to an argument about a relayed remark, not to an announcement by Anthropic.

Four days earlier the talk had run the other way. On a November 7 podcast, venture investor Chamath Palihapitiya said that if data-center supply tightened, SpaceX could end the deal on 90 days' notice and reprice at spot rates; SpaceX's Anthropic revenue "could 2 to 3X" and Anthropic would have no choice but to accept. That followed the November 3 US midterm elections, after which several states moved toward restricting new data-center approvals. Within a week, the same clause was read first as SpaceX's lever to raise prices and then as Anthropic's way out. The clause gives both sides the same right. Which one uses it depends on what compute costs in the spring of 2027.

3. Who needs whom: a third of SpaceX's revenue, an eighth of Anthropic's commitments

SpaceX's 10-Q for the third quarter, filed October 22, includes a customer concentration table.

The filing says all of Customer B's revenue sits in the AI segment, which SpaceX calls SI. At 34.5%, that is about $5.03 billion, or roughly two-thirds of the segment's $7.56 billion in the quarter. One customer also accounted for 27.7% of receivables at the end of September. The filing names no one. Bloomberg, citing a person familiar with the matter, reported that Customer B is Anthropic; neither company has confirmed it. Customer A is a long-standing buyer across all three segments, which The Motley Fool judged very likely to be the US government. A year earlier Customer A was the largest, at 23.9%.

The third quarter was a ramp period. With the full $3.1 billion a month arriving from December, the share could rise. Evercore ISI analyst Kutgun Maral ran the numbers in a note relayed by Yahoo Finance on October 27.

Maral did not see a near-term revenue risk, pointing to Anthropic's compute constraints and its $131.7 billion in liquidity, but wrote that the concentration "does raise the question of how dependent SpaceX is on a single tenant." The Motley Fool wrote on November 5 that 34.5% of the quarter's revenue could disappear by mid-2027. That is the author's inference from the 90-day clause, not a company forecast.

SpaceX has other tenants. Google rents capacity at about $920 million a month, and Musk has said since May that freed capacity can be re-let or used for Grok. The question is less whether the hardware would sit idle than whether it would earn the same price.

From Anthropic's side the weight is different. The amended S-1 puts total purchase commitments and leases at about $900.9 billion, nearly all of it compute and infrastructure. The SpaceX ceiling is about 13% of that. The comparison flatters the dependence somewhat, because the $900.9 billion runs to 2045 while the SpaceX terms end in 2029.

If Bloomberg's identification is right, the roughly $5 billion SpaceX booked from Customer B in the third quarter equals about half of Anthropic's $9.9 billion compute and infrastructure expense for the same period. The two companies' accounting and timing may not line up, so this is an approximation. The direction is clear enough: SpaceX supplies a large part of the compute Anthropic currently runs on.

That leaves the question of replacement. Anthropic said in May it would get up to 5 GW from Amazon and 5 GW from Google and Broadcom, the latter coming online from 2027. The filing describes a hardware supply agreement with AMD, effective July 2026, with a first tranche of capacity in calendar 2027. Fortune reported that the S-1 expects a growing share of spending to go to data centers Anthropic stands up through partners. Mid-2027 is about when those sources begin to arrive. If the relayed remark is accurate, Anthropic's bet is that it can do without SpaceX by then; Musk's "the opposite" reads as a bet that the replacement capacity will not arrive on time. Neither can be checked yet.

4. What is not confirmed

Anthropic is in the middle of its IPO roadshow, a period in which US securities rules limit what a company says outside its registration statement, so a public clarification of what was said in a private analyst meeting is unlikely. Two documents will show more. Anthropic's final prospectus will show whether the SpaceXAI paragraph changes. SpaceX's fourth-quarter report will show whether December revenue reflected the full $3.1 billion and how Customer B's share moved. After that, the dates to watch are the ends of the non-cancelable periods in January and March 2027.

For readers outside the United States, the clause is a reminder of how much of the AI build-out rests on short commitments: the largest disclosed compute contract between two of the most valuable companies in the sector can be unwound in three months. Our earlier reports on Anthropic's first S-1 filing, on its $70 to $78 IPO price range, on its $3.4 billion gas-generator purchase and on how GPU-backed debt works cover the surrounding numbers.