Anthropic's IPO roadshow video says Claude was ported to AMD GPUs in three days and gives no performance figures; AMD is also buying Anthropic shares at the IPO

Concept illustration: in a wide frame under a dark banner lettered ANTHROPIC beside a white angular mark, two people sit typing at desktop computers on the left; two tall black server racks each carry a sign lettered AMD, the left one beside the desks with a dark screen, the right one with a speech bubble on its screen above a label reading CLAUDE, and between them a standing person faces right toward a red laptop on a low stand whose screen reads MYTHOS. Below the frame at the bottom left, part of a grey projector is visible. Printed on the image: 3 days Porting Claude to AMD GPUs, down from months for dozens of engineers: Anthropic's roadshow claim.

In the IPO roadshow video it began showing on November 10, Anthropic says Claude's training and serving now run on four main chip families (Simon Willison's transcription, 2026-11-11). Our inference: if the three days holds, big buyers with frontier models could port to other chips for far less; ordinary developers are unaffected.

Anthropic began using AMD GPUs this year. Anthropic says the software work of moving Claude onto them shrank from several months for dozens of engineers to three days. According to the video, Anthropic handed the job to its model Mythos with almost no human intervention, and Claude ported or wrote nearly all of the kernels. A kernel here is the low-level code that makes a model's computations run on a particular chip.

NVIDIA CEO Jensen Huang has called CUDA's installed base the most important thing NVIDIA has. Huang said so on Lex Fridman's podcast in March (Lex Fridman Podcast, 2026-03-23). Kernels written for NVIDIA chips have to be rewritten for another vendor's chips, and that is where CUDA's hold on buyers comes from.

Anthropic's three days and Huang's remark cover different ground: Anthropic's is one chip buyer moving its own model to a new chip, while Huang was talking about the whole developer community. If models can do the rewriting, the beneficiaries visible so far are buyers that own such models; companies without one still have to rewrite this layer themselves when they switch chips.

A working port still leaves open whether switching pays off. Epoch AI, a research group that tracks AI compute and capability, has an inference-capacity index that sets NVIDIA's GB300 NVL72 rack at 1 and AMD's MI355X at about 0.55. The index is estimated with NVIDIA's simulation tools, not measured, and Epoch states that it doesn't account for software maturity (Epoch AI, 2026-11-11).

AMD and Anthropic are tied by money as well. Anthropic's amended IPO registration of November 10 says AMD will buy Anthropic shares at the IPO price when Anthropic lists, one of seven suppliers subscribing this way, about US$2.5 billion at the midpoint price (Anthropic amended IPO registration, 2026-11-10). AMD, which sells chips to Anthropic, will also become an Anthropic shareholder.

Not proven yet: the three days is Anthropic's own claim in a fundraising video; no one has measured performance How we checked →

Next to watch: what AMD says about Anthropic's usage on its February 2027 earnings call, and how Anthropic's first quarterly report after listing discloses usage by chip vendor. If by mid-2027 Anthropic still has no public launch or ramp on AMD, this reading has to change. The mid-2027 deadline is SecondSource's own.

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This item ran in the brief of Nov 12, 2026, alongside 16 other items. How we checked it, the quote checks and what was still missing that day are on that issue's How we checked page.

Cite this item

SecondSource (2026). "Anthropic's IPO roadshow video says Claude was ported to AMD GPUs in three days and gives no performance figures; AMD is also buying Anthropic shares at the IPO." https://secondsource.io/en/news/2026-11-12-2/. Accessed access date.