Remember that mystery customer Broadcom mentioned back in September? The one that ordered $10 billion worth of custom chips? We finally know who it is.

Anthropic. The AI company behind Claude just placed one of the largest chip orders in history.

The numbers are staggering

Broadcom CEO Hock Tan revealed the news during Thursday's earnings call. Anthropic ordered $10 billion worth of Google's latest tensor processing units, specifically the TPU Ironwood racks.

But that's not all. Anthropic placed an additional $11 billion order in Broadcom's latest quarter. That's $21 billion total in just a few months.

These aren't small purchases. This is infrastructure spending at a scale that signals Anthropic is preparing for massive expansion.

What are TPUs anyway?

Tensor Processing Units are Google's custom chips designed specifically for AI workloads. They're different from Nvidia's GPUs, which currently dominate the AI chip market.

Some experts believe TPUs are more efficient for certain AI algorithms. Google clearly thinks so. Last month, the company said it trained its state of the art Gemini 3 model entirely on TPUs.

Broadcom helps manufacture these chips for Google. Now they're delivering entire server racks, not just individual chips, directly to Anthropic.

Anthropic is Broadcom's fourth XPU customer. XPU is what Broadcom calls its custom AI chips. The fact that Anthropic is committing this much capital to TPUs instead of Nvidia chips is significant.

It suggests major AI labs are diversifying away from complete dependence on Nvidia. When you're spending tens of billions on infrastructure, you want options.

Broadcom typically doesn't disclose large customers. But Tan's September comment about the mystery $10 billion order drew massive investor attention. Everyone wanted to know who was spending that much.

Some speculated it was OpenAI. A Broadcom official told CNBC in October that it wasn't. OpenAI has its own separate agreement with Broadcom for chips.

There's a fifth mystery customer now

Broadcom also revealed Thursday that a fifth customer placed a $1 billion order for custom chips during the fourth quarter. Once again, they're not saying who.

"It's a real customer, and it will grow," Tan said cryptically.

The AI infrastructure arms race is accelerating faster than most people realise. When companies are casually dropping $10 billion, $11 billion, even $1 billion on chip orders, it's clear the industry believes AI scaling will continue for years.

Whether all this infrastructure spending actually generates returns that justify the investment? That's the trillion dollar question nobody can answer yet.