With the SpaceX IPO set in mere days, investors are already asking the obvious next question: when will it join the S&P 500?

It's a fair question. Depending on where the company ultimately prices, SpaceX could debut as one of the largest publicly traded companies in America. In terms of size, revenue potential, and investor interest, it would immediately become one of the market's most important companies.

Plus, I am famously not a fan of buying individual stocks. However, if SpaceX proves viable as a public company, I wouldn't say no to having it as part of my portfolio. As long as it came with the rest of the market in a broadly diversified, low cost index fund, perhaps even one of my favorite all-weather index funds listed here.

But here's the thing: going public and joining the S&P 500 are not the same thing.

A lot of investors assume that once a company reaches a certain size, inclusion in the index is automatic. That's not how the process works. In reality, there are several hurdles that SpaceX will need to clear before it can earn a place alongside companies like Apple, Microsoft, Nvidia, and Amazon.

Some of those requirements are straightforward. Others are surprisingly subjective. And together they help explain why even a successful SpaceX IPO may not immediately result in S&P 500 inclusion. As well as how long true index fund investors like myself may have to wait before it becomes part of our portfolio.

First, How Does a Company Get Into the S&P 500?

Most people think of the S&P 500 as a list of the 500 biggest companies in America.

That's close, but it's not entirely accurate.

The index is maintained by a committee at S&P Dow Jones Indices. That committee evaluates companies based on several criteria, including market capitalization, profitability, liquidity, and public ownership. Importantly, the committee also retains discretion over which companies get added and when.

In other words, there isn't a magical market cap threshold that automatically unlocks entry into the index.

A company can be large enough to qualify and still have to wait.

That's exactly why investors are already debating what the path might look like for SpaceX after its IPO.

So, What Could Stop or Delay SpaceX From Joining After Its IPO?

A few things, it turns out…

Hurdle #1: A Public Trading History

Even if SpaceX begins trading this week, it's highly unlikely that the company would be added to the S&P 500 immediately.

The committee generally wants to see a period of public trading first.

That makes sense when you think about it. An IPO only tells us what investors are willing to pay for a company on day one. It doesn't tell us how the stock will trade over time, how much liquidity will exist in the market, or how stable the shareholder base will be.

The committee typically prefers to observe a company for a period before making a decision.

Tesla is probably the best recent example. Many investors believed Tesla had earned a spot in the index well before it was ultimately added in late 2020. Yet the committee waited until it was comfortable that the company met the necessary requirements and represented an appropriate addition to the benchmark.

SpaceX could face a similar waiting period.

Hurdle #2: Profitability Matters More Than Many Investors Realize

One of the lesser-known requirements for S&P 500 membership is profitability.

The index isn't designed to be a collection of exciting stories or promising ideas. It's intended to represent large, established businesses. As a result, companies generally need to demonstrate positive earnings before they become eligible. For most public companies, determining profitability is relatively simple because investors can review quarterly and annual financial statements.

SpaceX is different.

Because the company has been private, outsiders have had limited visibility into its financial performance. While various reports have suggested that Starlink is becoming a significant profit driver and that the launch business remains strong, investors won't know the full picture until detailed public filings become available. In fact, it's more likely that SpaceX is operating in the red.

And that's where things get interesting.

SpaceX isn't simply operating a mature business. It's also spending enormous sums developing Starship and funding some of the most ambitious engineering projects on the planet. Those investments may be critical to the company's long-term success. They may even be essential to Musk's vision of making humanity a multi-planetary species.

But they also affect earnings.

The question isn't whether SpaceX has valuable businesses. The question is whether those businesses are producing the type of earnings profile that satisfies S&P requirements. Once the IPO filings are available, profitability will be one of the first things analysts dig into.

Bottom line: More than most, the valuation of SpaceX is largely due to castle in the sky projections, but that is not what inclusion in the S&P 500 is based on.

Hurdle #3: Free Float Could Be More Important Than Investors Think

If you've never heard the term “free float,” you're not alone. I hadn't. It's one of the most important concepts in index construction, yet it's rarely discussed outside professional investing circles.

Put simply, free float refers to the percentage of shares that are actually available for public trading.

Not every share counts.

Shares owned by founders, executives, directors, and certain large strategic investors are often excluded because they're not actively traded in the market.

Why does this matter?

Imagine two companies that are both worth $1 trillion. The first has 90% of its shares available to the public. The second has only 20% of its shares available because insiders control the rest.

Even though both companies have the same overall value, the first company is much easier for investors and index funds to buy and sell.

That's important because the S&P 500 isn't just a benchmark. It's also the foundation for trillions of dollars in index funds and ETFs. Those funds need access to enough shares to build positions efficiently.

This is where SpaceX becomes particularly interesting.

Elon Musk is expected to maintain substantial influence over the company after the IPO. In addition, employees, early investors, and long-term institutional holders may continue to own large portions of the business.

The result could be a relatively limited public float compared to the company's overall size.

That doesn't mean SpaceX couldn't join the index. It simply means investors should pay close attention to how much stock actually becomes available to public markets after the offering.

Hurdle #4: Governance Questions Aren't Going Away

Every large IPO attracts governance questions and SpaceX will be no different.

Corporate governance is one of those phrases that sounds boring until it suddenly becomes important. At its core, governance is about who controls a company and how they make decisions.

Investors typically look at things like:

• Board independence
• Voting rights
• Shareholder protections
• Executive accountability
• Related-party transactions

Founder-led companies often receive extra scrutiny because founders frequently retain outsized control after going public.

That's especially true when dual-class share structures (different shares have different voting rights) are involved. Supporters argue that these structures allow visionary founders to focus on long-term value creation rather than short-term market pressures. Critics argue that they reduce accountability and leave minority shareholders with limited influence.

SpaceX is likely to become one of the most prominent examples of this debate. Investors will also inevitably ask how Musk allocates his time. By the time SpaceX goes public, he will likely continue to play major roles across multiple companies and initiatives. Whether that represents a strength or a risk will depend largely on the individual investor.

Governance concerns alone probably won't prevent inclusion in the S&P 500. But they will certainly become part of the broader conversation.

Hurdle #5: The Committee's Discretion

This may be the most important point of all.

The S&P 500 is not governed entirely by formulas. If it were, investors could simply plug numbers into a spreadsheet and know exactly when they would add a company.

Instead, a committee ultimately makes the decision. That committee evaluates whether a company appropriately represents the U.S. equity market and whether adding it improves the index. This introduces a degree of subjectivity.

SpaceX isn't a traditional company.

• Is it an aerospace company?
• A telecommunications company?
• A technology company?
• Or a defense contractor?

In reality, it's a little bit of all of those things.

Its unique structure, massive size, and unconventional business model may make the committee more deliberate than usual. That doesn't mean the S&P 500 won't add SpaceX. It simply means the timeline may not be as predictable as many investors expect.

Why Investors Care So Much

For many investors, joining the S&P 500 isn't just symbolic. It has real financial implications. So many investors care that the S&P committee recently had to reaffirm its eligibility rules and they wouldn't bend them for any one company.

Today, trillions of dollars are tied to the index through mutual funds, ETFs, pension plans, and institutional portfolios. When a company joins the S&P 500, those funds effectively become mandatory buyers.

The larger the company, the larger the potential buying pressure. That's one reason Tesla's inclusion attracted so much attention. SpaceX could generate a similar effect, possibly on an even larger scale depending on its valuation and public float.

For investors, the SpaceX IPO may be the headline. But the race toward S&P 500 inclusion could end up being the more important story in terms of dollars and cents.

It also matters in terms of access. Wisely, many investors invest passively. Because active stock management just doesn't work. So, no S&P 500 means no SpaceX in the portfolio unless you start using a satellite investing strategy.

The Bottom Line

If SpaceX successfully goes public, it will immediately become one of the most closely watched companies in the market.

But investors shouldn't assume that an IPO automatically guarantees a spot in the S&P 500. The company will still need to demonstrate profitability, establish a sufficient public float, navigate governance questions, and build a public trading history. On top of all that, it will need the approval of the index committee itself.

None of these hurdles appear insurmountable.

In fact, it would surprise me if SpaceX doesn't eventually become an S&P 500 constituent. The real question isn't whether it gets there. The question is how long the journey takes and what that means for your investment portfolio. Personally, I am not buying any of this stock individually after the IPO but exercising patience and waiting for its inclusion in an index like the S&P 500. They have a vetting process for a reason and it helps safeguard investors as well. After that happens, it doesn't mean that SpaceX is a guaranteed good investment. It could still tank. But it means that when I buy SpaceX stock, I'll be buying the best stock in the index, whether it is SpaceX or not, along with everything else.

And that (passive investing) is what has proved to be a winning investment strategy time and again…

What do you think? Is the SpaceX IPO a big deal? Did you realize how complicated it is to become a part of the S&P 500? Should that matter to investors or not? Let me know in the comments below!