How a $1.75 Trillion IPO Forced the Index to Rewrite Its Own Rules

The Bargain That Is Being Tested

For decades, the architecture of passive investing rested on a simple and widely trusted bargain: index providers would build transparent, rules-based benchmarks, and investors (from retirement savers to sovereign wealth funds) would trust that those rules served the market's interest, not any single company's.

That bargain is now being tested.

In the span of three months, the three most influential equity index families in the world, Nasdaq, FTSE Russell, and S&P Dow Jones, have either adopted or proposed sweeping changes to how newly public companies enter their flagship benchmarks. The timing is not coincidental. SpaceX, OpenAI, and Anthropic are all preparing to go public in 2026 at combined valuations that could approach $3.5 trillion. The rules governing index inclusion, rules that direct over $30 trillion in benchmarked assets globally, are being rewritten just as the largest private companies in history prepare to cross the threshold into public markets.

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The rules governing index inclusion are being rewritten just as the largest private companies in history prepare to go public.

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This piece traces what changed, why, and what the evidence tells us about the consequences for passive investors who may be enrolled in these companies before price discovery has had time to work.

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The Shrinking Pool and the Private Market Problem

To understand why index providers are moving now, you have to understand a structural shift that has been building for over two decades. The number of publicly listed companies in the United States has been in sustained decline. McKinsey estimates the count dropped from roughly 5,500 in 2000 to about 4,000 by 2020. Apollo's data is starker: a 50% decline from the mid-1990s peak of over 8,000 domestically listed firms.

Between 1980 and 2000, an average of more than 300 companies went public annually in the US. Since then, the annual average has fallen below 100. The average age of a venture-backed company at IPO has roughly doubled over the past two decades.

The result is a structural mismatch that the index frameworks were never designed for: companies arriving at public markets as mature, often mega-cap businesses, rather than growing up inside them.

When SpaceX goes public at a target valuation of $1.75 trillion, it won't be a scrappy startup finding its footing. It will be larger than every publicly traded company except a handful: Nvidia, Apple, Microsoft, Amazon, Alphabet. The index inclusion frameworks were designed for a world where companies grew up in public markets. That world no longer exists.
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What Actually Changed: A Three-Index Comparison

The rule changes across Nasdaq, FTSE Russell, and S&P Dow Jones share a common direction but differ in their specifics. All three are lowering the barriers to entry for the largest IPOs, and all three moved within the same three-month window.

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Nasdaq-100 (Effective May 1, 2026)

Nasdaq adopted a fast entry rule: newly listed companies whose total market capitalisation ranks within the top 40 existing Nasdaq-100 constituents (roughly $100 billion as of year-end) are eligible for inclusion after just 15 trading days. The company's market cap is assessed on its seventh trading day. The fast-entry addition does not require the removal of an existing constituent: the index temporarily exceeds 100 names.

Additional changes include scrapping the 10% minimum float requirement, adopting a new market cap calculation that aggregates listed stock and unlisted shares across different share classes, and moving to quarterly updates on total outstanding shares. Notably, the Nasdaq-100 has no profitability requirement, and SpaceX is on track to post a loss exceeding $20 billion in 2026, which would be the largest annual loss ever recorded by a Nasdaq-100 constituent.

FTSE Russell US Equity Indexes (Effective May 26, 2026)

Russell's Index Governance Board approved fast entry for IPOs with an investable market capitalisation exceeding the Russell Top 500 breakpoint. Eligible IPOs are added after the close of the fifth trading day, even faster than Nasdaq's 15-day window. Russell relaxed its float and voting rights thresholds for Top 500-sized securities: IPOs with less than 5% float or voting rights are still eligible if lock-up expirations would bring them above the minimums within 12 months. Only fully underwritten deals qualify; direct listings must wait for the next quarterly review.

S&P 500 (Proposed, Consultation Closed May 28, 2026)

S&P Dow Jones Indices opened a formal review proposing to cut the seasoning period from 12 months to six, and to consider waiving its longstanding profitability requirement (four consecutive quarters of positive GAAP earnings) for megacap companies. If adopted, changes would take effect prior to market open on June 8, ahead of SpaceX's expected listing. Inclusion would still be committee-driven (unlike Nasdaq's rules-based approach), but the gating criteria would be materially loosened.

A Wave of Mega-IPOs Unlike Anything in Modern History

Three companies are driving the urgency, and their combined scale represents a capital absorption event with no modern parallel.

SpaceX: The $1.75 Trillion Test Case

SpaceX filed its S-1 on May 20, 2026, targeting a Nasdaq listing under ticker SPCX with expected pricing around June 11-12. The target valuation sits between $1.75 trillion and $2 trillion, with a planned raise of approximately $75 billion, more than double Saudi Aramco's $29.4 billion record in 2019, making this the largest IPO of all time by a wide margin.

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At the lower end of the valuation range, SpaceX is asking investors to pay approximately 87 times trailing revenue. Tesla and Nvidia trade at roughly 15 times.

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What changed the IPO calculus was AI. SpaceX has been repositioning itself as an AI infrastructure company, building out data centres to train and operate AI models, with Musk promoting a vision of orbital data centres leveraging SpaceX's satellite constellation. The corporate structure adds further complexity: SpaceX absorbed xAI (the former Twitter/X and AI company) in a cashless stock-for-stock transaction. Musk personally controls approximately 42% of equity and 85% of voting power.

OpenAI and Anthropic: The AI Double-Header

OpenAI is targeting a September-November 2026 listing at a valuation of $852 billion to $1 trillion. The company completed a $40 billion fundraise from SoftBank and a further $122 billion round, the largest single private financing in Silicon Valley history. It is projected to lose $14 billion in 2026 and does not expect profitability until 2029-2030.

Anthropic, the maker of Claude, is targeting a public listing as early as October 2026 at a reported valuation of approximately $900 billion, having reached $30 billion in annualised revenue run-rate as of early 2026.

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The Mechanics: Why Inclusion Timing Is Everything

When a company enters a major index, every fund tracking that index must buy shares. This is not discretionary. It is mechanical. The scale of this forced buying is significant:

• Approximately $600 billion in assets track the Nasdaq-100 through more than 200 investment products.
• Roughly $24-27 trillion is tied to S&P Dow Jones indices, including the S&P 500.
• FTSE Russell indexes underpin trillions more globally.

Under the new fast-entry rules, here is the concrete sequence for SpaceX. It lists on June 12. On its seventh trading day (approximately June 20), Nasdaq evaluates whether its market cap ranks within the top 40 of existing Nasdaq-100 constituents. At $1.75 trillion, it would rank in the top ten. After 15 trading days (approximately July 3), SpaceX enters the Nasdaq-100. Every ETF and index fund tracking the benchmark must buy SpaceX shares at whatever the market price is on the inclusion date, not because of a fundamental view, but because the rules require it.

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The combination of a 3-5% float, 30% retail allocation, and mandatory index fund buying within weeks of listing creates an asymmetric demand-supply dynamic with no historical precedent at this scale.

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The pool of freely tradable shares is tiny. The demand shock from index inclusion is large and mechanically certain. The lock-up period means most existing shareholders cannot sell until September-December 2026. This is the structural tension at the heart of the debate.

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What History Tells Us: The Tesla Precedent

The closest historical analog is Tesla's addition to the S&P 500 in December 2020. Tesla entered at a market cap of approximately $630 billion, the largest addition in S&P 500 history at the time, as the index's fifth-largest constituent at 1.68% weight.

Morgan Stanley estimated approximately $78 billion in passive fund inflows, representing about 17% of Tesla's free float. The stock rose roughly 700% in the year leading up to inclusion, driven partly by EV market enthusiasm and partly by anticipation of the index event itself. Tesla rallied an additional 57% between the announcement and the effective date.

Research Affiliates documented the aftermath. In a paper by Rob Arnott, Vitali Kalesnik, and Lillian Wu, they found that index funds systematically buy high and sell low during rebalancing events. Tesla underperformed in the six months following inclusion, while the stock it replaced outperformed by a wide margin. An investor with $100,000 in an S&P 500 index fund was approximately $410 poorer as a direct result of the December 21 rebalance, a cost that, as Research Affiliates put it, 'totally unnoticed by investors because it is baked into the index's performance.'

The question is whether the same pattern holds when the inclusion window compresses from months to 15 days, and when the float is one-fifth as large.
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The Conflict of Interest Question

Nasdaq is simultaneously a stock exchange that earns listing fees and trading data revenue, and an index provider whose inclusion decisions direct hundreds of billions in passive capital. The Nasdaq-100 franchise alone has approximately $830 billion in assets under management. This dual role creates an inherent tension.

Reuters reported that SpaceX conditioned where it would list on one thing: fast-track entry into the Nasdaq-100. NYSE President Lynn Martin publicly implied Nasdaq changed the rules to win the listing. For Nasdaq the exchange, the prize is significant: not just listing fees but trading volume, data licensing, and competitive prestige. Nasdaq attracted $4 trillion in market cap switches to its exchange in the past year alone.

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SpaceX conditioned where it would list on one thing: fast-track entry into the Nasdaq-100. The rules that happened to make that possible were adopted shortly before the decision was made public.

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Nasdaq's president Nelson Griggs maintains the exchange and index businesses operate with strict separation, and that the fast-entry discussion began 'well over a year ago.' The core argument is representativeness: if the Nasdaq-100 is meant to capture the 100 largest non-financial companies on the exchange, then excluding a company the size of SpaceX for up to a year 'does not really represent what the index is meant to be.'

That argument has merit. But it sidesteps a harder question: the governance gap. No SEC approval is required for index methodology changes. The IOSCO Principles for Financial Benchmarks explicitly aim to address conflicts of interest in the benchmark-setting process, but these principles are voluntary in the US. The only formal check is the index provider's own internal consultation process.

When asked whether passive investors have a meaningful choice, Griggs framed it plainly: 'If you choose to invest in SpaceX, that is your decision. If you do not want to, you do not have to. You would have to buy the index.' That framing exposes the central tension perfectly. For the growing share of Americans invested through passive vehicles, buying the index is buying SpaceX, and that is precisely the point critics are making.
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Second-Order Effects: Concentration, Crowding, and Liquidity Risk

The rule changes interact with an already extreme market structure. The S&P 500's 10 largest stocks already account for nearly 40% of the index's weight, the highest concentration since the Great Depression. Analysts project that if SpaceX, OpenAI, and Anthropic all enter the S&P 500, the top-10 concentration could jump to 50%.

• Forced buying into a small float compresses price discovery into a narrow window.
• If the post-IPO price is set primarily by mechanical index demand, the stock's trading identity may be permanently shaped by a plumbing event rather than operational performance.
• When lock-ups expire and early investors begin selling, the buyers on the other side may be retirement savers who entered through index funds at mechanically inflated prices.
• None of these three companies is profitable. SpaceX is on track to lose more than $20 billion in 2026. OpenAI does not expect profitability until 2029-2030. Passive investors are being enrolled in these bets without being asked.

NEPC, a major institutional investment consultant, framed this as a portfolio construction challenge in an April 2026 paper: index inclusion timing can generate large, mechanical demand shocks, and a single mega-IPO can quickly become a top index weight, exacerbating concentration risk and reinforcing existing factor and sector tilts. This is about flows, not fundamentals.

And SpaceX may not be an anomaly so much as a template. If enormous companies arriving at public markets as pre-built mega-caps become the rule rather than the exception, the fast-entry framework shifts from a one-off accommodation to a permanent feature of index construction.

The Architecture of Passive Investing Is No Longer Passive

Index investing was built on a promise of passive, rules-based, low-cost access to the broad market. That promise assumed the rules were designed for market integrity, not optimised for any single listing. The changes underway do not necessarily violate that principle. There is a legitimate argument that an index meant to represent the market should include the market's largest companies promptly.

The bull case is straightforward and powerful: SpaceX has built real, dominant businesses in satellite broadband and rocket transportation. Starlink alone is already profitable. The AI infrastructure buildout could be genuinely transformational. Investors who bought Nvidia, Amazon, or Tesla at eye-watering multiples and held through the volatility were handsomely rewarded. The FOMO is rational.

The structural question is different from the stock-picking question. When index methodology changes convert a single company's IPO into mandatory purchases across trillions of dollars in retirement savings, the architecture of passive investing is no longer passive.

But the structural question is different from the stock-picking question. When index methodology changes convert a single company's IPO into mandatory purchases across trillions of dollars in retirement savings before the market has had time to determine what the company is actually worth as a public entity the architecture of passive investing is no longer passive. It is a transmission mechanism, and the question of who controls the transmission, and in whose interest, is no longer academic.

For passive investors and for the retirement savers who may not even know they are about to become SpaceX shareholders the question is not whether these companies deserve to be in the index. It is whether the process that puts them there is serving the investor, or the issuer.

Key Sources & References

Arnott, Kalesnik & Wu 'Revisiting Tesla's Addition to the S&P 500' (Research Affiliates, 2021)  ·  Greenwood & Sammon 'The Disappearing Index Effect' (Journal of Finance, 2025)  ·  Gabaix & Koijen 'The Inelastic Markets Hypothesis' (Harvard, 2022)  ·  NEPC 'How Will Fast-Track Index Inclusion of Mega-IPOs Impact Your Portfolio?' (April 2026)  ·  SpaceX S-1 Filing (SEC, May 20, 2026)  ·  Nasdaq-100 Methodology Update (May 1, 2026)  ·  FTSE Russell Market Consultation (May 26, 2026)  ·  S&P Dow Jones Indices Proposed Amendments (consultation closed May 28, 2026)  ·  Bloomberg Television, interview with Nelson Griggs, Nasdaq President (2026)

© 2026 Lean Research. For institutional use only. Not investment advice.

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