In equities, the question is not just company worth but when who is forced to buy and when
This week’s IPO by SpaceX will not be just a record-setting transaction; it will also become a stress test for equity market structure. Its early trading performance will be shaped, at least initially, by index-inclusion rules and it will pose a challenge for both passive capital and active management. In this deal, the market is not buying only ‘a good story’ but also a supply-and-demand structure.
The most important point is that, against an estimated valuation of $1.75 tn dollars, the company is looking to raise ‘only’ $75 bn dollars. In other words, what actually comes to market is only about 5 percent of its equity.
Hundreds of billions in passive assets
Its stock performance will initially depend not only on operating results, but also on the rules that determine how long a newly listed company takes to enter the major indices that serve as benchmarks for hundreds of billions of dollars in passive assets.
The key point is that index-linked passive funds are buyers ‘without discretion’. An index fund does not decide whether SpaceX is cheap or expensive: it buys what the methodology of the index it tracks tells it to buy. If a company enters the Nasdaq 100, the Russell 1000 or the S&P 500, the funds that replicate those indices must buy it, at whatever valuation the market assigns. That buying is offset by proportional sales of other holdings or by the full removal of securities that are kicked out of the index.
The larger the new company is, and the smaller the proportion of its equity that is actually floating publicly, the faster it can be admitted into an index – and the larger the forced buying and selling flows can become. Bloomberg estimates that index funds control, on average, 24 percent of companies’ equity, adjusted for free float, which highlights the scale of these ‘forced purchases’.
New rules for big listings
The clearest regulatory move has come from Nasdaq. In 2026, the exchange operator approved a fast entry rule for the Nasdaq 100 that allows accelerated inclusion of a newly listed company if its market capitalization ranks it among the index’s 40 largest constituents, with five trading days’ notice and effective entry after 15 trading days.
SpaceX’s IPO appears set to reserve 30 percent for retail investors, versus the 5 percent-10 percent range typical in many IPOs
Previously, at least three full months of trading had been required, along with minimum trading and free-float conditions. FTSE Russell has also shortened the timetable to five days. By contrast, the other major benchmark, the S&P 500, has decided to keep its 12-month minimum seasoning requirement before a company can be included and it is not relaxing its profitability or minimum free-float criteria for now.
The logic behind this reform is straightforward: if a huge technology company debuts with a massive valuation built in private funding rounds, the market does not want to wait too long before seeing it enter the sector’s main benchmark index.
A big retail reserve
Another factor that could support the stock in the short term is that SpaceX’s IPO appears set to reserve 30 percent for retail investors, versus the 5 percent-10 percent range typical in many IPOs. That is not a minor detail: if some retail investors buy because SpaceX is associated with Tesla, and a significant share of the stock ultimately lands in index funds that must buy for methodological reasons, the seller is left with a very strong demand base that is relatively price-insensitive in the short run.
For active managers, the dilemma is especially uncomfortable. If they do not participate in the IPO, they may miss one of the biggest market stories of the year. But if they get involved too early, they buy at a very high valuation and take the risk that the price will not hold once the initial momentum fades.
That leaves active managers with two bad options: either they ride the enthusiasm and accept the risk of paying too much, or they stay out and bear the reputational cost and relative performance drag of missing a major placement. That is one of the reasons a SpaceX IPO could have such a large impact on market behavior.
Market structure and the big beasts
The SpaceX case shows how a giant private company can turn index design into a direct engine of its own valuation. Market structure itself increasingly channels capital toward companies that are already larger, more liquid and more visible. For smaller, less liquid companies and their investor relations teams, the challenge gets harder every day. They face the risk of gradually disappearing from the minds of active investors who need to outperform the indices.
This IPO also shows that, in equities, the question is not only what a company is worth, and when the underlying business will have the ability to convert expectations and a huge valuation into earnings. One must also ask who is forced to buy it and when.
With SpaceX, OpenAI or Anthropic on the horizon, that dynamic could intensify further in the coming months.
Ricardo Jiménez Hernández is strategic adviser at Harmon and a former director of investor relations at Ferrovial. He is also a member of the IR Impact editorial board
