S&P Dow Jones Indices just told the biggest IPO candidates in history to wait their turn. On June 4, the index provider confirmed it will not change its eligibility rules for major US indices, including the S&P 500, after a formal consultation period that gathered input from a wide range of market participants.

The decision lands at a particularly loaded moment. SpaceX is planning a June 2026 IPO with a target valuation of $1.75 trillion, offering less than 5% of shares initially. Under the existing rules, Elon Musk’s rocket company would face at least a one-year wait before even being considered for the S&P 500, regardless of how massive it is at listing.

What the rules actually require

The S&P 500 isn’t just a list of America’s biggest companies. It’s a curated index with specific gatekeeping criteria, and S&P just reaffirmed every single one of them.

First, there’s the 12-month seasoning period. A company must trade publicly for a full year before it’s eligible. No exceptions for trillion-dollar valuations.

Second, profitability. Companies need to demonstrate positive earnings under Generally Accepted Accounting Principles (GAAP) in both their most recent quarter and over the trailing four quarters.

Third, minimum investable weight factor (IWF) thresholds remain unchanged. The IWF measures how much of a company’s stock is actually available for public trading, as opposed to shares locked up by insiders. When SpaceX is planning to float less than 5% of its shares, this becomes a very relevant hurdle.

SpaceX reported a $4.94 billion GAAP loss in 2025. Even if the IPO goes flawlessly, the profitability requirement alone would keep it out of the S&P 500 for a considerable stretch, potentially well beyond the initial 12-month waiting period.

The index provider split

What makes this decision notable isn’t just the ruling itself. It’s that S&P’s competitors are moving in the opposite direction.

Both Nasdaq and FTSE Russell have adjusted their rules to enable faster index entry for large IPOs. The logic is straightforward: when a company lists at a trillion-dollar-plus valuation, forcing passive funds to ignore it for a year creates a disconnect between the index and the actual market it’s supposed to represent.

S&P’s Index Committee looked at the same question and came to the opposite conclusion. They decided that financial health and established operational history matter more than sheer size.

This creates a genuine philosophical split among the three major index providers. A company like SpaceX could theoretically appear in Nasdaq and FTSE-linked products while being excluded from S&P-linked ones, creating tracking differences between funds that retail investors might assume are roughly interchangeable.

What this means for investors

S&P 500 index trackers manage substantially more assets than vehicles tracking the Nasdaq-100. By keeping the gates closed to freshly listed megacaps, S&P is effectively delaying that wave of passive buying. For SpaceX, this means the company would need to rely on active investor demand for potentially a year or more after listing. Given the planned sub-5% float and the nearly $5 billion in reported losses, that creates a scenario where price discovery could be volatile.

There’s also a less obvious implication for the broader IPO market. If you’re a late-stage private company eyeing a public listing, the S&P’s decision signals that getting big isn’t enough. You need to get profitable, at least by GAAP standards, before you can access the largest pool of automatic capital in equities.