SpaceX’s Customer B Drove 34.5% of Q3 Revenue, Reportedly Anthropic

Image: Elon Musk/X

SpaceX’s third-quarter filing shows that one unnamed client, labeled only as Customer B, accounted for 34.5% of the company’s revenue in the three months ended September 30, more than any other single buyer and more than Customer A at 16.6%.

That concentration figure comes from SpaceX’s Form 10-Q. All of Customer B’s revenue sat in the Super Intelligence segment, the AI compute and software arm formerly called the AI segment. Bloomberg later reported, citing a person familiar with the matter, that Customer B is Anthropic. Neither SpaceX nor Anthropic has confirmed that identification.

On a $14.6 billion revenue quarter, 34.5% works out to roughly $5.0 billion, or about $1.7 billion a month. Customer B had not cleared the 10% disclosure threshold a year earlier, and for the first nine months of 2026 it still represented 24.2% of consolidated revenue, while Customer A, whose sales span all three SpaceX segments, was 17.3%.

The Anthropic read fits earlier public paper. Anthropic’s own IPO filing said it agreed to spend up to $120.5 billion on SpaceX AI compute through 2029, about $3.1 billion a month once all contracted capacity is delivered, though those deals can be canceled with 90 days’ notice after early 2027.

SpaceX’s Q3 results already showed how fast that SI business is scaling. Segment revenue hit $7.6 billion in the quarter, up 830% from a year earlier, and Elon Musk has said SpaceX locked in about $40 billion of GPU debt for hardware arriving in the first half of 2027.

Until SpaceX or Anthropic puts a name on Customer B in a filing or on the record, the Bloomberg identification remains an unconfirmed report. The 34.5% share itself is not.

Does one AI customer paying more than a third of SpaceX’s quarterly revenue change how you see the Super Intelligence business?