Anthropic Could Join the Nasdaq-100 Only 15 Trading Days After Its IPO, Just Like SpaceX Did

Anthropic, the company behind the Claude family of artificial intelligence (AI) models, has reportedly picked where its stock will trade. It has chosen Nasdaq for its planned initial public offering (IPO), according to a Business Insider report this month citing a person familiar with the plans.

Some estimates put the potential valuation near $2 trillion, the report said, though that figure isn't final. The Wall Street Journal has since reported that the listing slipped to November, after third-quarter results. Anthropic hasn't confirmed any of it.

If Business Insider is right, the choice matters for investors who never touch an IPO. The Nasdaq-100 is limited to nonfinancial companies listed on Nasdaq -- a company that lists with the New York Stock Exchange can't get in while it stays there. And more than 200 investment products with over $800 billion in assets track the index, including the Invesco QQQ Trust (NASDAQ:QQQ).

And under a rule that took effect on May 1, a big enough newcomer can join the index just 15 trading days after its IPO. SpaceX (NASDAQ:SPCX) did exactly that this summer. If Anthropic's timeline holds, QQQ investors could own a slice of the AI company before the year is out.

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A 15-day wait

To qualify for fast entry, a new listing's full market value must rank among the top 40 companies already in the index, and the stock typically joins after its 15th day of trading. A debut late in November could instead wait on the index's December reconstitution.

Showing how quickly that can move, SpaceX listed on June 12 and joined the Nasdaq-100 before the market opened on July 7 -- about three and a half weeks, start to finish.

Anthropic would clear the size bar easily. A funding round in March 2025 valued the company at $61.5 billion. The round it announced this past May valued it at $965 billion, an almost 16-fold jump in about 15 months. And the estimates now attached to an IPO are about double even that.

Of course, the timeline comes from press reports, not the company. Anthropic submitted its draft registration statement confidentially to the Securities and Exchange Commission on June 1, and as of this writing, the filing still wasn't public. Nothing about November is locked in.

How big a slice?

Anthropic's piece of the fund would start much smaller than $2 trillion suggests.

The index ranks a company for entry on its full market value, but it weights the company on a narrower number -- the lesser of its listed value or three times the value of its freely trading shares. In other words, a giant company with a tiny float gets a small weight, no matter the headline valuation.

That cap is why SpaceX's arrival barely registered in the fund. The rocket company went public with less than 5% of its shares available for trading, and despite being worth more than $2 trillion at the time, it entered the index at about 1%. An investor with $100 in QQQ owned about $1 of SpaceX.

Anthropic could start the same way. Companies at this scale tend to float only a small slice of themselves at first, with insiders locked up for months. Follow the pattern, and its starting weight could land around 1%, too, rather than the 4% or 5% a full-size weighting might suggest.

But the cap loosens over time. Nasdaq refreshes float figures at its quarterly rebalances, so a newcomer's weight steps up as lockups expire.

Nobody gets kicked out

Fast entry breaks one more piece of index convention: nothing has to leave. Notably, the index simply holds more than 100 names for a while.

The room comes from everywhere else. Every other holding's weight shrinks a little to make room. A newcomer at 1% trims the other names by about 1% of themselves, a rounding error for any one of them.

What would QQQ holders get? Automatic ownership of one of the world's most prominent tech companies a few weeks after it lists.

SpaceX is a useful reminder here, I'd argue. QQQ wasn't a buyer at the June debut. It bought weeks later, at prices the market had already set. And the shares remain well below their post-IPO high.

Ultimately, for investors who own QQQ, which trades around $746 as of this writing, I don't think the news calls for any action. Picking up the market's new giants automatically is arguably the point of owning an index fund, and the float cap keeps the early bet small.

Sure, Anthropic's early trading could disappoint the way SpaceX's has. But nothing is settled until there's a filing to read and a listing date on the calendar. For now, the slice QQQ holders stand to get is a small one.

Daniel Sparks and his clients do not have positions in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.