The one compute bill Anthropic can cancel belongs to SpaceX, now up to $84.5B

SPCX is rising on a page of someone else's paperwork

Anthropic's confidential IPO prospectus↗, seen by Reuters, commits the lab to at least $518 billion of compute over a decade across six partners, with about 80% non-cancelable or payable regardless of usage ¹. The line that moved the market sits inside it: up to $84.5 billion for Nvidia-based capacity from SpaceX through 2029, mostly cancellable on 90 days' notice ². SPCX closed up 2.6% at $149.24 on 29 September ³.

Every locked number is a floor. The SpaceX number is a ceiling.

The binding contracts are minimums. Google collects at least $111.1 billion between April 2026 and July 2033, and "if our actual spend falls short, we must pay Google the difference" ¹. Amazon gets $110 billion through April 2036, Microsoft $31.4 billion non-cancelable through May 2033, and Broadcom holds $161.2 billion of equipment leases neither side can exit short of default ¹. The SpaceX figure is the only "up to" in the book, the one number that can shrink ¹.

The exit clause was the landlord's idea

SpaceX's own May paperwork showed Anthropic paying $1.25 billion a month through May 2029 for roughly 325,000 GPUs at Colossus, the Memphis complex built by xAI, the Musk AI company SpaceX absorbed in February: worth nearly $45 billion ⁴. The prospectus nearly doubles that ceiling. Musk said in May the short-term exit was written at SpaceX's request, not Anthropic's: "if compute gets super tight, I said we might need it back at some point" ⁵.

The next tranche of capacity does not exist yet. Orbital compute satellites begin deploying "as early as 2028," per SpaceX's registration statement↗ ⁵, and the rocket meant to loft them first reached orbit on 28 September 2026↗, coming home early after a couple of laps instead of six ⁶.

The book is 113 times Anthropic's revenue

Against 2025 revenue of about $4.6 billion and a $42 billion net loss ⁷, IPO buyers are asked to underwrite roughly $113 of commitments per dollar of revenue ⁸. SpaceX collects either way: Google already pays it $920 million a month through June 2029 and Reflection AI $150 million a month ⁵⁹, and an unnamed fourth tenant starts at $1.1 billion a month in December ³.

The bulls are underwriting unbuilt gigawatts

TD Cowen opened at Buy with a $200 target↗, expecting compute leasing to carry most of SpaceX's revenue by the first quarter of 2027, $66 billion that year, on capacity climbing from 2.1 to 6 gigawatts ³. The same note sees no free cash flow until 2030 and $225 billion of new debt ³. The ramp leans on leases every party can leave: the three disclosed by June, Anthropic, Google and Reflection, can each be ended on 90 days' notice ⁵.

The prospectus is still confidential and off EDGAR, filed in June and unpublished since ¹⁸. When it lands, the tell is whether the SpaceX "up to" hardens into a floor like everything else.

Anthropic signed decade leases with its cloud rivals and kept one exit open: the landlord whose satellites are not in orbit yet.