Anthropic's $15B compute bill

Until last month, the bill a frontier AI lab pays to keep its models running was a closely held number. SpaceX's S-1, filed with the SEC on May 20, put one on the public record: Anthropic is locked into roughly $1.25 billion a month — about $15 billion a year, and $40 billion-plus over the full term — through May 2029, for access to the Colossus data centers. Against Anthropic's revenue, now running near $43 billion a year, that single line item eats somewhere between a third and a half of the top line. It is the cleanest public data point yet on the question that hangs over the whole industry: does a lab's revenue actually cover what it costs to compute.

"The short deal length was our request, not theirs, as I thought we might need the compute back at some point." — Elon Musk

The twist is who collects the rent. SpaceX bought xAI in February and folded it in; Colossus was built to train Grok, whose app usage has been sliding. So the idle capacity is now leased to Anthropic — the maker of Claude — while the same campus, the filing notes, trains Grok 5. Anthropic is, in effect, helping bankroll the infrastructure of a direct competitor.

And it does so on a short leash. Either side can walk on 90 days' notice — a term Musk said SpaceX asked for, in case it wants the compute back. So Anthropic's largest cost, on the eve of its own IPO, rests on capacity a rival can reclaim in a quarter.