SpaceX IPO filing reveals xAI's $12.7B CapEx; Anthropic to pay xAI $1.25B/month for compute

For the first time, outsiders can see what it actually costs to run an Elon-scale AI company. The SpaceX prospectus revealed xAI poured $12.7B into CapEx in 2025 alone — more than SpaceX spent constructing the entire Starlink constellation. PitchBook's piece, headlined 'financials look reckless,' argued xAI's burn could become the largest venture-stage write-down ever if model performance doesn't keep up with Anthropic and OpenAI.

The twist is that xAI is also a vendor of compute, not just a buyer. TechCrunch reported Anthropic will pay xAI $1.25B per month for compute capacity — a recurring number on the order of $15B/year flowing between two direct model competitors. Combined with NVIDIA's confirmation that Anthropic is now one of its hyperscale frontier customers, the new reality is that frontier-lab compute is a multi-counterparty bazaar: GPUs flow from NVIDIA → Colossus/Colossus2 → Anthropic training runs, with cash flowing back to xAI.

xAI also kept shipping products this week: Grok now has third-party connectors to Vercel, Canva, Gamma and S&P Global; 'Grok Skills' (May 18) add persistent custom expertise across conversations; and a Grok ↔ OpenClaw integration (May 19) lets Grok and X Premium subscribers use Grok inside the open-source agent platform. The official xAI account also pushed Grok-powered code inside opencode.

The contradiction developers are noting on X: the same company whose CapEx is described as 'reckless' is the one underwriting Anthropic's training capacity. If frontier-lab GPU economics ever invert — even briefly — the counterparty exposure cuts both ways.