Why SpaceX in the Nasdaq-100 Isn’t the Threat to Index Funds It Seems

SpaceX’s arrival in the Nasdaq-100 has raised fresh worries about whether index funds are still as safe as investors think, but the bigger story is that the funds themselves are built to absorb shocks like this. The company’s inclusion matters because it highlights how passive investing handles a giant, controversial, fast-moving stock — not because it makes index funds suddenly unstable.

In practical terms, the July 7 addition of SpaceX to the Nasdaq-100 forced index-tracking funds to buy shares, potentially cushioning the stock during its post-IPO period and pushing more money into a company many investors would never choose on their own. The episode has also reignited concerns about market concentration, megacap IPOs, and Elon Musk’s unusual control over the company.

To understand what is actually happening, it helps to look beyond SpaceX itself and into the mechanics of index funds, why they became so dominant, and why experts say one new name in a benchmark does not overturn the basic case for passive investing.

What happened when SpaceX joined the Nasdaq-100?

SpaceX entered the Nasdaq-100 on July 7, after the exchange changed its rules so a newly public company that is large enough can join the benchmark 15 days after its trading debut. The timing was significant because index funds tracking the Nasdaq-100 had no choice but to buy the stock once it qualified.

That forced demand matters for two reasons. First, it can support a new listing’s share price during an unstable period when employees, early investors, and other holders are waiting for their shares to become tradable. Second, it can create market distortions around the index change itself, as traders anticipate the buying and position themselves ahead of time.

SpaceX’s inclusion also arrives at a moment when the market is preparing for more giant private-tech listings. Anthropic and OpenAI are both widely expected to reach public markets later this year, which means the same index mechanics could soon play out again on an even larger scale.

Why are investors nervous about SpaceX?

Investors are nervous because SpaceX is not a conventional public company. It is a massive, highly promoted, closely controlled business with an unconventional governance structure and a valuation that many market observers consider extremely stretched.

That combination makes the stock feel less like a standard blue-chip addition and more like a high-stakes bet tied to one of the most polarizing figures in business. Elon Musk’s reputation alone has become part of the investment debate, since many shareholders worry about sudden strategic shifts, public-relations shocks, and erratic decision-making.

But the worry is not just emotional. SpaceX’s public-market debut intersects with the plumbing of modern investing, where huge amounts of retirement money sit in funds designed to track indexes automatically. That creates a situation in which ordinary investors may end up owning a company they would never have selected directly.

How does index-fund buying affect a new stock?

It can create a stabilizing bid at a moment when the stock may be under pressure from profit-taking, lockup expirations, or speculation. Index funds buy because they must replicate the benchmark, not because they are making a judgment on the company’s prospects. That mechanical demand can support the price in the near term.

It can also create strange trading behavior before and after the listing. When investors know passive funds are about to buy, professional traders often attempt to profit from the predictable flow. Research cited by market analysts has suggested that index-related buying can contribute to the initial pop in hot IPOs.

Burton Malkiel, the economist and longtime champion of passive investing, said he would think carefully before buying SpaceX directly because he sees the company as highly hyped. He argued, however, that the stock’s presence in an index fund is not a reason to avoid index funds themselves.

What is an index fund, and why did it become so popular?

An index fund is a portfolio built to mirror a benchmark such as the S&P 500 or the Nasdaq-100. Rather than trying to pick winning stocks one by one, the fund simply owns the companies in the index in roughly the same proportions as the benchmark itself.

The idea became mainstream through the work of Burton Malkiel, whose 1973 book A Random Walk Down Wall Street helped popularize the argument that markets are too hard to beat consistently. The basic premise is simple: because stock prices are difficult to predict, most active managers fail to outperform broad market averages over time.

The case for passive investing has also been reinforced by some of the most famous figures in finance. Warren Buffett has long urged ordinary investors to put most of their money into a low-cost S&P 500 index fund, and passive assets have continued to grow as investors lose patience with expensive active management.

Why do passive funds appeal to ordinary investors?

They are cheap, diversified, and relatively easy to understand. Instead of betting on one company, one sector, or one fund manager’s skill, investors are buying exposure to an entire market segment.

That diversification is what makes index funds feel safe. One weak stock can hurt performance at the margin, but it usually cannot sink the portfolio on its own. The fund’s structure spreads risk across dozens or hundreds of names.

That is also why large public-market shifts matter more than any one company’s story. If a new megacap enters an index, the change matters because of the scale of the benchmark, not because index funds are suddenly broken.

How much does SpaceX really matter inside the index?

SpaceX is enormous, with a market value above $1.5 trillion as of the reporting date, but its footprint inside the Nasdaq-100 is not as overwhelming as that headline number suggests. Only a small slice of the company was sold in the IPO, which means the stock’s index weighting does not translate directly from its private-market hype.

That distinction matters because indexes are based on float, market capitalization, and the rules of the benchmark provider, not on the total value of a business in the abstract. A company can be huge and still have a more limited presence in an index if relatively few shares are publicly available.

Even so, SpaceX’s role is expected to grow as more shares come off lockup. Some employees and early holders cannot sell immediately after the IPO, but those restrictions end in stages. When more shares become tradable, the market structure changes again.

What is a lockup period?

A lockup period is a post-IPO restriction that prevents insiders from selling their shares right away. It is designed to reduce immediate selling pressure and help stabilize the stock after the listing.

As those restrictions expire, supply increases. If demand does not rise with it, the share price can fall. In SpaceX’s case, index funds may help absorb some of that additional selling, though the exact effect is impossible to know in advance.

Why do some people think SpaceX could distort index funds?

The concern is partly about concentration and partly about governance. As the market becomes more dominated by a small number of very large companies, index funds become more exposed to the same names over and over again. That can make a supposedly diversified portfolio feel more like a bet on a narrow group of corporate giants.

SpaceX also intensifies that concern because it is controlled so tightly by Musk. According to the reporting and the company’s structure, Musk holds the majority of voting power, leaving outside shareholders with little practical ability to influence strategy or leadership.

That is a far cry from the governance norms many investors expect from public companies. In a typical listed business, shareholders can file proposals, vote on board composition, and sometimes sue over conduct that harms their interests. SpaceX’s setup narrows those options.

Retirement fund officials from CalPERS and New York City and state offices previously criticized the company’s governance, arguing that its structure gives Musk extraordinary control and leaves other shareholders largely sidelined.

Why does governance matter if index investors do not vote individually?

Because the large index providers do. When millions of investors own shares through passive funds, the real voting power is concentrated in a small number of fund managers and index sponsors. That gives those institutions substantial influence over corporate outcomes, even though the end investors are passive.

This concentration raises awkward questions. Should a handful of giant asset managers decide how to vote on acquisitions, executive pay, board seats, and shareholder proposals for a huge swath of the market? Critics argue that this gives too much power to too few firms.

Supporters say the opposite: because the funds are long-term owners on behalf of millions of people, they have a responsibility to use their votes carefully and to protect shareholder value.

How does the Nasdaq-100 compare with the S&P 500?

The Nasdaq-100 and the S&P 500 are both major benchmarks, but they are not the same kind of index. The Nasdaq-100 is more concentrated in large technology and growth companies, while the S&P 500 is broader and more diversified across sectors.

That distinction matters because SpaceX’s inclusion affects funds tracking the Nasdaq more directly than those following the S&P 500. If the company is not included in the S&P benchmark, investors in S&P funds will be insulated from its effects, at least directly.

For investors, that means different index funds can now diverge more meaningfully in performance, especially if SpaceX moves sharply after the initial trading period. A Nasdaq-heavy portfolio may behave very differently from one built around the S&P 500.

What is the real risk to retirement savers?

The real risk is not that one company will blow up index funds. The real risk is that investors may misunderstand what they own and assume passive investing eliminates all volatility or all concentration risk. It does not.

Index funds do a good job of reducing company-specific risk compared with picking individual stocks. But they still reflect the structure of the market itself, including its biggest winners, its dominant themes, and its most crowded trades. If the market is concentrated in a handful of giant names, index funds will be concentrated too.

That said, concentration is not new. Malkiel argues that markets have always been dominated by a relatively small number of huge winners. The fact that a few stocks account for much of the return does not invalidate the index strategy; it is part of why broad ownership works in the first place.

What about the AI concentration problem?

AI concentration is already baked into major indexes, and SpaceX simply adds another mega-cap story to the list. Nvidia, Microsoft, Apple, Amazon, Alphabet, Meta, and Broadcom already carry significant weight in the largest benchmarks, giving passive investors heavy exposure to the same technology cycle.

That has led some investors to wonder whether they are unwittingly making a huge bet on one theme. If AI turns out to be a bubble, then broad-market funds will feel some of the pain. But that would reflect market composition, not a failure of index-fund mechanics.

Malkiel’s broader view is that markets have repeatedly overestimated major technological shifts — from railroads to the internet — and that today’s enthusiasm around AI fits that pattern. In his view, the answer is not to abandon index funds, but to remember that markets regularly overdo the excitement around the next big thing.

Why do some investors still prefer to avoid SpaceX?

Some investors want to avoid SpaceX because of Musk’s control, the company’s governance structure, or a dislike of tying retirement savings to a highly volatile and politically charged brand. Others simply do not want exposure to a stock they see as overvalued.

There are ways to reduce or eliminate direct exposure, though none are perfect. Investors can favor S&P 500 index funds over Nasdaq-100 products, or they can look at environmental, social, and governance funds if avoiding SpaceX is a priority.

But ESG funds come with their own trade-offs. They often charge higher fees, may underperform simple index funds, and can still end up holding companies some investors would rather avoid. A fund that excludes one controversial company may still include another with similarly tricky politics or business practices.

• Choose broader benchmarks if you want less concentration in tech and mega-cap growth stocks.
• Check fund holdings rather than assuming a label tells the full story.
• Compare fees carefully, since more selective funds often cost more.
• Consider your goal: lower controversy, lower cost, or higher diversification may not all be possible at once.

How should investors think about megacap IPOs now?

They should think of them as market events with mechanical consequences, not just company stories. A megacap IPO affects indexes, trading flows, lockup schedules, and fund allocations all at once. That means the impact can be bigger and stranger than the headlines suggest.

SpaceX also shows how public-market structures can bend around private-market demand. Exchange rules were adjusted, index inclusion followed, and passive funds were forced into the trade. The result is a stock that is partly driven by fundamentals, partly by the mechanics of indexation, and partly by the cultural magnetism of Elon Musk.

That mix makes the stock fascinating to watch and difficult to model. But it does not overturn the core logic of index investing. If anything, it demonstrates why passive funds remain popular: they spread exposure to the whole market, including the parts investors may find uncomfortable or overhyped.

Malkiel’s bottom line is that investors should not confuse one flashy inclusion with a broken investment strategy. In his view, the market has always relied on a small cluster of winners, and no one can reliably predict in advance which companies will become them.

Bottom line

SpaceX’s addition to the Nasdaq-100 is important because it spotlights how much power index funds now have in modern markets. It may affect pricing, trading patterns, and governance debates. But it does not mean passive investing has suddenly become unsafe.

For most investors, the real lesson is simpler: index funds are still designed to hold the market’s winners and losers together. SpaceX is just the latest reminder that in an era of megacap IPOs and AI-driven concentration, the market’s biggest names can reshape benchmarks without breaking them.