Anthropic’s $3.1B-a-Month SpaceX Bill Is Real. “Locked In” Isn’t.

Monday, October 26. Anthropic’s IPO filing goes live on the SEC’s database, and by Tuesday a post with a siren emoji is telling the internet that SpaceX has “locked” Anthropic into $3.1 billion a month. Four claims ride on it: the lock, the 80%, the comparison with Google and Amazon, and the margin warning. We read the paper.

The number is real, and bigger than anyone reported

Anthropic’s S-1 filing says it “agreed to spend an aggregate of up to $120.5 billion over terms extending into 2029” with SpaceX’s AI arm. Once all the contracted capacity is delivered, which Anthropic expects in December, the bill runs about $3.1 billion a month. That is roughly $37 billion a year.

In September, Reuters had put the ceiling at $84.5 billion, Blockspace noted. The filing added about $36 billion. Anthropic says that between May and October it “entered into and amended several agreements” with SpaceX’s AI arm.

The first version was smaller. SpaceX’s own IPO filing showed $1.25 billion a month through May 2029, about $45 billion, for roughly 325,000 NVIDIA GPUs across Colossus and Colossus II. The monthly rate has gone from $1.25 billion to about $3.1 billion in five months.

SpaceX feels it already. Its third-quarter report shows a single customer, which it doesn’t name, made up 34.5% of $14.58 billion in revenue, according to an analysis of the filing. That is just over $5 billion. CNBC’s reporting identifies the customer as Anthropic. At the full rate, Anthropic would be paying $9.3 billion a quarter.

The headline number holds.

“Locked in” is the wrong verb

$120.5 billion is a maximum, not a promise. And the contract has a door. The S-1 says it plainly: “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.” SpaceX’s May filing said the same about the original deal.

Elon Musk has leaned on that door in public. On May 28 he posted that SpaceX had agreed to a “180-day lease with a mutual 90-day cancellation notice thereafter,” Reuters reported. “The short term was our request, not Anthropic’s,” he wrote, adding that SpaceX would “provide a reasonable off-ramp,” but “if compute gets super tight I said we might need it back at some point.”

So the seller says he can take it back, and the buyer’s filing says it owes up to $120.5 billion. Both are true, because of the notice period. The money exposed on day one is the notice window, not the ceiling.

That makes the SpaceX deal the odd one out in Anthropic’s compute book. The same filing lists Google at “at least approximately $114.5 billion” through July 2033, Amazon at “at least $110.0 billion” through April 2036, and Microsoft at “at least $44.9 billion” through May 2033. All three are spent “regardless of actual usage,” and each is non-cancelable except if the provider commits an uncured material breach. SpaceX is the only big supplier Anthropic can walk away from on a quarter’s notice.

SpaceX has the mirror-image problem. Google pays it $920 million a month from October through June 2029 for about 110,000 GPUs, terminable on 90 days’ notice after December 31, TNW reported from SpaceX’s filing. SpaceX’s two anchor tenants can both leave in a quarter.

Bigger than Google and Amazon? Per month, yes

The post says the SpaceX bill dwarfs Anthropic’s deals with Google and Amazon. By the monthly rate, it does. Google’s minimum works out to about $1.3 billion a month over its term and Amazon’s to about $900 million, against SpaceX’s $3.1 billion.

By the money Anthropic can’t walk away from, it’s the other way around. Google and Amazon are binding for seven to ten years. Anthropic also estimates another $125 billion to $150 billion of TPU compute from Google and other providers between 2028 and 2031, which isn’t in the committed figures at all. SpaceX is the biggest tap and the shortest pipe.

The 80% is a quarter out of date

The post says the bill is about 80% of Anthropic’s current monthly revenue. The filing doesn’t give a run rate, but it gives enough to check.

Anthropic’s revenue for the second quarter was $11.555 billion, about $3.85 billion a month. Against that, $3.1 billion is 80%. So the post’s math works, for April through June.

The third quarter was bigger. The S-1 leaves the dollar figure blank, but it says revenue for the three months ended September 30 “was 86 times” its revenue for the last quarter of 2024, which it puts at $197 million. That implies about $16.9 billion. The Financial Times reported $16.8 billion, according to Reuters. That is about $5.6 billion a month, and against it the SpaceX bill is closer to 55%.

What the post gets right is scale. Six months at $3.1 billion is $18.6 billion. Anthropic spent $8.945 billion on all compute and infrastructure in the first half. That is a step of more than double. It held $131.7 billion in cash and short-term investments on June 30, so the step is affordable. It is still a step.

The margin warning is in the filing

This claim checks out. Anthropic’s S-1 says that when demand exceeds the capacity it buys 12 to 18 months ahead, “we procure short-term compute, which typically carries a higher cost per unit of compute. We expect our use of short-term compute to increase in the near term and to in turn compress our operating margin and Adjusted Operating Margin as a result.” It also says new compute is booked as an expense before the revenue it supports arrives.

The same filing says both margins “have expanded significantly year over year” for the nine months ended September 30. In the second quarter alone, operating margin went from minus 152% a year earlier to 8%. The warning is about the next stretch, not the last one.

One caution. The passage does not name SpaceX, so tying it to this deal is the post’s inference. SpaceX’s CEO told investors on October 20 that it rents compute at effectively spot-market rates, according to Blockspace. The filing doesn’t say whether Anthropic books the SpaceX capacity as short-term.

The thing nobody in the room saw

The compute Anthropic is renting sits on a power system SpaceX is still building. Its filing shows plans to buy $2.8 billion of gas turbines over three years. In Southaven, Mississippi, SpaceX says a permanent 1.2-gigawatt plant with 41 turbines is under construction, while 69 temporary turbines keep running, TechCrunch reported. An agreed order with Mississippi regulators lets the last of them stay until July 2027.

The NAACP sued over turbines it says ran without permits. In June the Justice Department moved to intervene and dismiss the case, citing national and energy security, Mississippi Today reported. The court has not ruled.

SpaceX reported 1.7 gigawatts of compute at September 30. Third-quarter capex was $19.6 billion on $14.6 billion of revenue, and it has guided to $35 billion to $40 billion of capex in the fourth quarter. SpaceX is spending more than it earns to build the capacity Anthropic is renting.

The line

The number is the headline. The notice period is the story.

Researched and written by Massih Shahbazi.

Sources

• Anthropic, PBC: Form S-1, filed Oct. 26, 2026 (SEC)
• Space Exploration Technologies Corp.: Form S-1, May 20, 2026 (SEC)
• sec-api.io: Financial analysis of SpaceX Q3 2026 earnings
• Blockspace: Anthropic discloses up to $120.5 billion in SpaceX compute spending
• Reuters via Yahoo Finance: Musk says SpaceX did not commit to long-term Colossus lease with Anthropic
• TNW: Google to pay SpaceX $920 million a month for compute
• Reuters via The Star: Anthropic revenue jumps to $16.8 billion in third quarter, FT reports
• TechCrunch: SpaceX won’t remove all of xAI’s unpermitted turbines for another year
• Mississippi Today: Department of Justice sides with Musk’s xAI in Southaven lawsuit

Photos

• “Futuristic Server Room with Green and Blue Lights” by Wavebreakmedia, Envato Elements (featured image; stock photo, not a SpaceX facility)
• Colossus site, aerial: SpaceXAI (x.ai/colossus)
• S-1 excerpt: Anthropic, PBC, Form S-1, SEC EDGAR (highlight added)
• Southaven turbine site, aerial: Brad Zweerink / Earthjustice