Should you apply for the Anthropic IPO? You'll probably own it anyway
British investors can now apply for shares in Anthropic's flotation through Hargreaves Lansdown, AJ Bell, interactive investor and other mainstream platforms. Anyone with a global index fund already has a stake in the company through Amazon and Google, and is likely to own its shares directly within weeks of listing. The real question is whether you want a bigger bet on one company than the market already gives you.
The Anthropic IPO is coming to Nasdaq, and the company behind the Claude AI models wants British savers to take part. Anthropic plans to sell 825 million shares at between $70 and $78 each, valuing the company at up to $1.404 trillion on a fully diluted basis. It is reported to be aiming for about 20 per cent of the shares to go to individual investors, far more than is usual.
The last company to try this was SpaceX. About 100,000 UK investors received shares in its flotation in June, paying £271.4 million between them. The shares peaked at $225.64 within days. On 6 November they closed at $134.27, below the $135 offer price, having fallen as low as $104.83 in August.
What the UK offer involves
Pricing for the Anthropic IPO is expected on 18 November. The UK offer is run by RetailBook under the FCA's new public offer platform rules. Orders go through AJ Bell, eToro, Hargreaves Lansdown, Interactive Brokers, interactive investor and Revolut. At interactive investor, applications can go into an ISA or a SIPP.
There's no UK prospectus. You get the US prospectus and a short disclosure summary, and the FCA approves neither. With SpaceX, applications closed the day before pricing, and each platform set its own cut-off.
The shares carry little control. Seven co-founders will hold 50.1 per cent of the votes through a single share, and a Long-Term Benefit Trust will elect a majority of the board. Public shareholders get a share of the profits but little say in how the company is run.
When the Anthropic IPO reaches your index fund
Amazon and Google, two of the biggest companies in any global index, will each hold more than five per cent of Anthropic once its preferred shares and notes convert. If you own a global tracker, part of what you hold already rises and falls with Anthropic.
Direct ownership is likely to follow quickly. Most index providers now let very large new listings in within weeks rather than months, and MSCI added SpaceX to its World and All Country World indexes 17 days after it listed. The exception is the S&P 500, which requires 12 months of trading, a profit in the latest quarter and positive earnings across the latest four combined. Anthropic reports large accounting losses, so S&P 500 trackers will be the last to hold it.
Index | UK-available trackers include | When Anthropic could join |
FTSE All-World | Vanguard FTSE All-World ETF | Eligible for fast entry |
MSCI World and MSCI ACWI | iShares Core MSCI World ETF | About 10 trading days after listing |
Nasdaq-100 | Invesco EQQQ Nasdaq-100 ETF | About 15 trading days after listing |
S&P 500 | Vanguard S&P 500 ETF | At least 12 months, plus a profit test |
Source: index provider rules as reported by Reuters, MSCI and Gallagher. Timings describe the rules, not confirmed dates for Anthropic. As at 11/11/2026.
Your fund's holding will be small at first, because index weights count only shares that are free to trade, and most of Anthropic's will be locked up until next year. When MSCI simulated adding SpaceX, OpenAI and Anthropic to its US index, the three together came to under 1.2 per cent of it. Nvidia alone was 7.7 per cent. Russell Investments projects that the three could reach approximately 2.5 per cent of the MSCI World by early 2028, as more of their shares start to trade.
The case for applying, and why it falls short
Successful applicants buy at the offer price. Index funds buy later, at whatever the market charges, often after the shares have already jumped. Across US flotations from 1980 to 2025, the average first-day rise was 19.0 per cent, according to data compiled by Jay Ritter of the University of Florida.
That average overstates what small investors actually get. In 1986 the economist Kevin Rock pointed out that informed investors pile into the flotations they expect to do well and avoid the rest. When an issue is in demand, small investors are scaled back. When it isn't, they get everything they asked for. The British economist Mario Levis provided the first direct test of this 'winner's curse', using UK flotations from the late 1980s, and found evidence for it.
SpaceX's UK offer shows the scale-back at work. British investors put in nearly $1 billion of orders and received $364 million of shares, with applications above $2,700 cut back.
The advantage of buying at the offer price is real. It's just smaller and less dependable than the headline average suggests. Robin Powell, TEBI's founder, explained why the best flotations are often the hardest to buy into in a recent column for MoneyWeek.
Nor is a first-day rise guaranteed. About 70,000 people bought £50 million of shares in Deliveroo's flotation in 2021 through an app. The shares fell by as much as 30 per cent on the first day.
The tracker route isn't free either. SpaceX shares stayed above the offer price until mid-July, so index funds that added them in late June and early July paid more than successful applicants did, then rode the shares down. The difference was how much was at stake. For a global index fund, SpaceX was a sliver of the portfolio. Someone who put £5,000 of a £50,000 ISA into the flotation had a tenth of their money riding on one company.
What happens after the first day
Ritter measures long-run returns from the first day's closing price, so his figures show how investors fare when they buy once the shares are trading, which is roughly where an index fund stands. In his data for 1980 to 2024, shared with Charles Schwab, flotations by companies with less than $100 million of sales lagged the market by 34.3 percentage points over three years. Those with $100 million or more lagged by 3.2 points, roughly keeping pace. Anthropic is firmly in the second group.
None of this says Anthropic's shares will disappoint. It does mean that missing the first day costs less than it seems: buyers of big flotations after the first close have, on average, roughly kept pace with the market. TEBI has covered the research on IPO returns before, and nothing in it suggests applying is a reliable way to beat the market.
If you still want to apply
Some readers will apply regardless, and that's their call. The shares are priced in dollars, so their value to you will move with the exchange rate as well as the share price. Lock-ups on most existing holders end next year, which will bring more shares onto the market, as it did with SpaceX. A holding small enough that you could leave it alone if the price halved is unlikely to do lasting damage to a plan.
A slice in proportion
The Anthropic IPO will be promoted as a chance to own a piece of the future. But most people with a global index fund already have a stake through Amazon and Google, and will soon hold Anthropic shares directly, in proportion to the shares investors can trade. That holding grows as more shares are released and as its market value rises.
What an application adds is concentration: a larger bet on one company, bought when interest is at its height. A few investors will want that bet. Most don't need it.
Sources
Anthropic, PBC. (2026). Form S-1 registration statement (amended 10 November 2026). US Securities and Exchange Commission.
Levis, M. (1990). The winner's curse problem, interest costs and the underpricing of initial public offerings. The Economic Journal, 100(399), 76–89.
MSCI. (2026). What the SpaceX IPO means for investors. MSCI.
Ritter, J. R. (2026). Initial public offerings: Updated statistics. University of Florida.
Rock, K. (1986). Why new issues are underpriced. Journal of Financial Economics, 15(1–2), 187–212.
Russell Investments. (2026). How mega IPOs may deepen market concentration. Russell Investments.
Schwab. (2026, 14 August). Are initial public offerings (IPOs) worth it? Charles Schwab.
A second opinion before you apply
Whether to put part of your savings into a single flotation, or to rely on the index funds you already hold, is a decision many investors would like to talk through. TEBI’s Find an Adviser directory lists advisers who have publicly committed to evidence-based investing: low-cost, globally diversified portfolios rather than bets on individual companies.
To follow how the evidence on new issues and index investing develops, sign up to the TEBI Digest, which brings you TEBI’s latest articles and curated reading with Robin Powell’s commentary.
