Anthropic Could Join Nasdaq-100 Within Weeks of IPO Under New Fast-Track Rule

Anthropic, the artificial intelligence company behind Claude, has selected Nasdaq as the venue for its initial public offering, according to reporting from Business Insider this month. The timing and mechanics of that choice matter far beyond the company itself—they could determine when hundreds of billions of dollars in index-tracking funds automatically own a piece of the business.

The company's valuation has climbed steeply. A funding round in March 2025 valued Anthropic at $61.5 billion. By May of this year, that number had jumped to $965 billion, a sixteenfold increase in fifteen months. Current estimates attached to the IPO float around $2 trillion, though nothing is final. The Wall Street Journal reported in September that the listing has slipped to November, after the company releases third-quarter results, though Anthropic itself has confirmed none of these details publicly. The company filed a confidential registration statement with the Securities and Exchange Commission on June 1, and as of late September, that filing remained unpublished.

What makes the Nasdaq choice significant is a rule the exchange adopted this spring, effective May 1. Under that rule, a newly listed company large enough to rank among the top 40 existing holdings in the Nasdaq-100 index can join the index just 15 trading days after its IPO. The Nasdaq-100 itself is restricted to nonfinancial companies trading on Nasdaq—a company listed on the New York Stock Exchange cannot enter while it remains there. More than 200 investment products with over $800 billion in assets track the index, including the Invesco QQQ Trust, one of the most widely held exchange-traded funds in the world.

SpaceX demonstrated how quickly this mechanism works. The rocket company listed on June 12 and joined the Nasdaq-100 before the market opened on July 7—roughly three and a half weeks from debut to index inclusion. If Anthropic's November timeline holds and the company qualifies by size, QQQ investors could own shares before the year ends, without any action on their part.

But the actual exposure would be modest at first. The index ranks companies for entry based on full market value, but weights them using a narrower calculation: the lesser of the company's listed value or three times the value of its freely trading shares. This cap exists precisely because newly public companies typically float only a small percentage of their shares initially, with insiders locked up for months or longer. SpaceX went public with less than 5% of its shares available for trading. Despite a market value exceeding $2 trillion at the time, it entered the Nasdaq-100 at roughly 1% weight. An investor holding $100 in QQQ owned about $1 of SpaceX. Anthropic would likely follow the same pattern, starting at around 1% rather than the 4% or 5% a full-size weighting might suggest.

That weight is not permanent. Nasdaq refreshes float figures quarterly, so as insider lockups expire and more shares become tradable, Anthropic's position in the index would gradually increase. The mechanism also breaks a traditional index convention: when a new company joins, nothing gets removed. Instead, the index simply holds more than 100 names for a period, and every other holding shrinks slightly to make room. A newcomer at 1% trims all other positions by roughly 1% of themselves—a rounding error for any individual stock.

For QQQ holders, the practical effect is automatic ownership of one of the world's most prominent technology companies weeks after it lists, at prices the market has already set. SpaceX offers a cautionary note: the fund did not buy at the June debut but weeks later, and those shares have since traded well below their post-IPO highs. Nothing is locked in until Anthropic files publicly and sets a listing date. For now, the slice QQQ investors stand to receive is small, and the company itself has said nothing to confirm any of these timelines.