How to buy Anthropic shares in the UK: IPO date, valuation and platforms

Anthropic's IPO is the listing of the season. Here's what UK investors need to know before applying - from the $1.3 trillion valuation and which platforms are taking part, to the W-8BEN form and why you may not get all the shares you ask for.

The listing of the season has been announced. US AI giant Anthropic will be listing on Thursday 19th November. If you are interested in participating, here are some things you’ll need to know.

What is Anthropic's IPO valuation?

Anthropic has been given an indicative valuation of $1.3 trillion but this could go higher by launch day. Why? The basic rules of supply and demand. When demand is hot, prices go up. This is a very high valuation but the potential revenue from Claude is really still being worked out. So you could argue for or against. The honest truth is no-one really knows.

In 2026, retail investors move markets more than they ever have done. Just a decade ago, stock markets were dominated by institutions who were arguably more governed by numbers and less by FOMO. (Arguably!) Investors are enthralled by the AI story, so I suspect this listing will be over-subscribed. Which means not everyone will get all the shares they have asked for.

Which UK platforms will offer Anthropic shares?

At the time of writing, it is confirmed that these platforms will offer their customers access:

Do I need a W-8BEN form to buy Anthropic shares?

These shares will be listed in the US and so there is a W-8 Beneficiary form to complete. This is a tax form that confirms to the powers that be that you are not liable to pay tax in the US. You will need to complete this before being allocated shares.

How many Anthropic shares will I get in the IPO?

It is likely that demand will outstrip supply. No-one will know for sure, but if you are applying for about £1,000 worth, you might get them all. If you are applying for, say £10,000, you might only get a proportion of this allocated. There is potentially some precedent from SpaceX earlier this year where larger requests got about 38p of every £ requested. So if they applied for £100,000 worth of shares in the IPO, they got £38,000. But no-one can confirm this to you until after the event.

Will Anthropic shares go up after the IPO?

Honestly, no-one knows. It might pop. It could thump down to Earth with a bang. I will be applying for some shares. But I’m clear that this is speculative. And it might go horribly wrong. I will not hold these shares for long, in fact I might sell them on the day of launch. Before too much time passes, they will be included in all my index funds. So this is a bit of a play and not with money I am reliant on in the shorter-term. It’s pure speculation based more on human psychological observation than financial modelling.