Why was Claude Mythos really delayed? OpenAI points to Anthropic's massive compute constraints, says report

OpenAI has told its investors that the company has a significant edge over rival AI startup Anthropic owing to its early push to expand computing resources. The news comes to light via an internal memo reported by Bloomberg that notes that OpenAI is claiming it has outpaced its competitor by “rapidly and consistently” adding computing capacity to meet surging demand for AI.

The report comes shortly after Anthropic revealed its most powerful AI model, Mythos, earlier this week. The Claude maker said in a blog post that the model poses a high cybersecurity risk.

“That gap matters because compute is now a product constraint,” OpenAI said in the memo.

The AI startup noted that it had 1.9 gigawatts of computing capacity available in 2025, triple the amount from the previous year. The ChatGPT maker also said that it expects this to grow to the low-double-digit range next year, eventually reaching roughly 30 gigawatts by 2030.

In contrast, OpenAI estimates that Anthropic ended 2025 with 1.4 gigawatts and will hit between 7 and 8 gigawatts next year.

“Even at the high end of that range, our ramp is materially ahead and widening,” the company said.

Notably, as Anthropic's Claude gained in popularity in the last few months, the AI startup has seen various outages and has even had to cut support for third-party AI agent platforms like OpenClaw.

In the investor note, OpenAI cited a report from analyst Ben Thompson suggesting these computing constraints may have influenced Anthropic's decision to limit the release of the Mythos model to select partners.

While speaking at the New York Times DealBook Summit last year, Anthropic CEO Dario Amodei had said, “There’s [a] genuine dilemma, which we as a company try to manage as responsibly as we can… And then I think there are some players who are ‘YOLO-ing,’ who pull the risk dial too far, and I’m very concerned,”

OpenAI has fired back at this characterisation in its memo, stating that Amodei miscalculated the market's massive appetite for AI products.

"In hindsight, that caution looks less like discipline and more like underestimating how fast demand would arrive," OpenAI wrote.