xAI Colossus cluster has surplus GPU capacity; the company launches a leasing business to monetize idle GPUs.

Elon Musk's xAI built some of the largest AI clusters on the planet. Now it is renting much of that hardware to other companies, including direct rivals.

xAI's fleet of nearly 550,000 NVIDIA GPUs was running at a utilization rate of approximately 11%, according to the research findings.

Zoom in on Colossus 1, its first major data-center cluster, and the picture looks similar. About 60,000 GPUs were active there as of May 2026, which works out to roughly 11% utilization.

xAI moved its training workloads to the newer Colossus 2 cluster, leaving the older facility with a lot of expensive silicon and not much to do.

The biggest tenant is Anthropic, which signed a multi-year agreement for the full capacity of Colossus 1. That covers around 220,000 GPUs at $1.25 billion per month, running through May 2029.

There is a catch for xAI. The Anthropic contract includes a 90-day termination clause, which means the headline figure is less locked in than the multi-year label implies.

Google is next in line. It has secured approximately 110,000 GPUs at Colossus 2, with the deal set to start in October 2026. That agreement is valued at $920 million monthly and runs until June 2029.

Reflection AI has committed to roughly $150 million per month in lease payments to xAI.

One more customer remains unnamed. That undisclosed client is expected to contribute approximately $1.11 billion per month starting in December 2026.

The research findings put xAI's forecasted annualized revenue at $27 to $41 billion by mid-2026. With the undisclosed customer included, combined annualized revenue run-rates are described as exceeding $40 billion.

The leasing income strengthens the narrative surrounding SpaceX's impending IPO, according to the research findings.

xAI intends to scale its GPU resources to over 1.2 million and reach more than 2 GW of power capacity by the end of 2026.

Once Colossus 1 belongs to Anthropic and a large slice of Colossus 2 goes to Google, xAI's own needs and its remaining customer commitments have to be served by whatever it builds next.

The 90-day termination clause on the Anthropic deal means the largest single contract could unwind relatively quickly.

The Google deal does not begin until October 2026, and the undisclosed customer's payments start in December 2026. Until then, a portion of the forecast is a promise on paper rather than cash in the bank.

Hitting over 1.2 million GPUs and more than 2 GW of power by the end of 2026 is an ambitious build schedule. Any delay in chips, power hookups, or construction would squeeze xAI between its customers' expectations and its own training plans.