The US stock market is undergoing a phase of structural contraction. According to a white paper published by Nasdaq in 2025, this decline exceeds one-third over 25 years. High-valuation companies such as Stripe or Databricks are choosing to remain private longer, citing high compliance costs and onerous transparency requirements, as noted by Reuters. This phenomenon mechanically delays the entry of technology leaders into institutional investors' portfolios, as current Nasdaq 100 index rules only allow for composition revisions once a year.

An Acceleration Mechanism for Exceptional Valuations

The new "fast-entry" clause aims to eliminate this waiting period, which could previously exceed 12 months. According to Cameron Lilja, Global Head of Index Solutions at Nasdaq, shareholding structures have evolved: companies now reach critical mass ("mega-caps") even before seeking public capital. To reflect this reality, Nasdaq has approved a new fast-track valuation protocol.

Starting on the 7th day of trading, Nasdaq evaluates the market capitalization of the new stock and determines if it ranks among the top 40 values in the index. If the company meets the eligibility criteria set by Nasdaq regulations—notably exclusive listing on the Global Select or Global Market segments and the nature of securities limited to common stock—its integration into the Nasdaq-100 becomes effective as of the 15th day. Under this rule, the usual seasoning requirements for listing history and trading volume are waived. This move comes as SpaceX, OpenAI, and Anthropic prepare their market debuts in the coming months.

Concretely, consider the case of OpenAI. If the company goes public in H2 2026 at a valuation estimated between $500bn and $1bn, as reported by Bloomberg, it would rank among the top capitalizations of the Nasdaq 100. Its integration into the index would then be mechanical, effective from the 15th day. For index fund managers replicating the Nasdaq 100, this means a forced rebalancing within 2 weeks, compared to potentially more than a year under current rules.

Overhauling Weighting and Float Criteria

Beyond execution speed, this reform removes two technical hurdles that would have made the entry of these companies impossible under the old rules, regardless of their capitalization.

The first concerns the free float and the calculation of capitalization—two bottlenecks that compound for mega-caps emerging from the private sector. SpaceX is the most direct illustration. According to FCC reports cited by CNBC, Elon Musk holds approximately 42% of the capital and controls 80% of the voting rights through a dual-class share structure. The company is reportedly targeting a capital raise of approximately $75bn for a target valuation exceeding $1.75 trillion, according to Bloomberg. At such a valuation, the initial free float would represent about 4% of the capital, well below the 10% threshold required by the old rules. Furthermore, since its merger with xAI in February 2026, the deal structure suggests that a significant portion of the capital could remain unlisted after the IPO. Under the old calculation method, only shares actually listed on the exchange were used to determine index eligibility, which would have mechanically underestimated SpaceX's true weight in the ranking.

The reform removes the free float threshold and now integrates all share classes, both listed and unlisted, into the capitalization calculation. Without these two changes, SpaceX simply could not have joined the Nasdaq-100, regardless of its valuation. In return, companies with a low free float will receive a reduced weighting in the index, proportional to their share of capital actually available on the market.

Finally, to ensure the index's relevance, any company whose weighting falls below 10bp for two consecutive months will be automatically excluded and replaced. These adjustments also apply to listing transfers, such as Walmart's move last year.

A Regulatory Race That Nasdaq Is Not Running Alone

This reform is not happening in a vacuum. Reuters confirms that FTSE Russell and the NYSE 100 are also modifying their index entry rules in response to the same anticipated IPOs. It is an open race among index providers to be the first to capture future AI and space mega-caps, and the institutional flows that accompany them.

Holders of a Nasdaq 100 ETF will feel the impact concretely. With a total index capitalization of approximately 22 billones de dólares, an entry by OpenAI at its high valuation estimate of $1 trillion would represent nearly 4% of the index within two weeks. Managers of funds replicating the index, including Invesco's EQQQ—the main Nasdaq 100 ETF accessible to European investors with approximately $8,312m in assets under management—would be mechanically forced to sell a fraction of every existing holding to make room for the new entrant, within a timeframe reduced to 15 days versus more than a year under the old rules. This sudden concentration, depending on the liquidity available at the time of inclusion, could amplify short-term volatility across all index constituents.