TL;DR

Anthropic may lodge public IPO paperwork before August is out, according to Bloomberg reporting, for a listing that could match or exceed the $75bn SpaceX raised in June — the largest technology flotation on record. Size and timing remain unconfirmed. A listing by OpenAI is not anticipated before the closing weeks of 2026, and possibly not until 2027.

The filing matters more than the number

Headline valuations from private rounds are negotiated between a small number of parties. A public filing is different: it forces disclosure of quarterly revenue trajectory, business line breakdown and cost structure to anyone who wants to read it.

That is the first genuine outside look at whether the reported figures hold up. Anthropic’s most recent quarter showed $11.5bn of revenue, fourteen times the year-earlier level. OpenAI’s second quarter came in at $6.2bn, up 18% on the preceding three months per Wall Street Journal reporting this week. If those hold in a prospectus, the company long treated as the challenger is now growing considerably faster than the incumbent.

Two risks the prospectus will have to carry

The first is political. Anthropic has been in open conflict with the Trump administration over military applications, after the White House moved to stop the Pentagon running its models for weapons that fire without a human decision, or for blanket surveillance of Americans. It went on to brand the firm a threat to the supply chain. That designation is an unusual line to have in a risk factors section.

The second is competitive and structural. Chinese developers keep shipping open-weight models that perform well and cost a great deal less, which puts long-term pressure on the pricing that underwrites both Anthropic’s and OpenAI’s enterprise revenue.

Looking forward

For UK investors this is a repricing event whether or not they buy in. Resultsense reported earlier this week that Anthropic plans supervoting shares for its founders before listing, and that its revenue run rate had passed $65bn — governance and scale respectively, and this is the third piece: the calendar.

A listing at that size resets the comparables for every AI holding, including British ones. Quantexa is currently weighing London against New York for its own float, and where a record-setting AI listing lands will not make that decision easier for the London Stock Exchange.