SpaceX IPO could put Musk shares in 401(k) index funds soon

SpaceX’s planned public debut could send Elon Musk’s rocket company into retirement accounts almost as soon as it starts trading, not because savers choose it, but because broad index funds may have to buy it automatically. That would give ordinary 401(k) and IRA investors an indirect stake in one of the world’s most closely watched private companies, starting from a very small public float.

The company filed its S-1 registration statement with the U.S. Securities and Exchange Commission on May 20, 2026, targeting a public valuation around $1.75 trillion. One report said SpaceX posted $18.7 billion in 2025 revenue and a $4.9 billion GAAP net loss, with Starlink generating $11.4 billion, or about 61% of total revenue. Only about 5% of SpaceX is expected to trade publicly at the listing, and as much as 30% of the shares sold in the offering are earmarked for retail investors, a far higher allocation than the typical 5% to 10%.

That structure matters because index funds do not wait around once a company joins the benchmarks they track. Broad total-market funds, including those held inside 401(k)s, could be positioned to buy SpaceX within as little as five trading days if the stock is added to major indexes. For millions of savers, that would mean owning SpaceX without making any active decision, while also adding exposure to a company that would immediately be weighted by its still-small public float.

The biggest near-term split is between MSCI and S&P Dow Jones Indices. MSCI said on June 8, 2026, it would apply its existing rules for early inclusion of large initial public offerings in its Global Standard Indexes, a move that could clear the way for SpaceX to enter sooner. S&P Dow Jones Indices took the opposite approach on June 4, 2026, keeping the S&P 500’s 12-month seasoning period, profitability requirement and 10% minimum float threshold. Under those rules, SpaceX would not be eligible for S&P 500 inclusion until at least June 2027.

The difference is more than technical. The S&P 500 is the benchmark behind passive funds with trillions of dollars in assets, and inclusion can trigger automatic buying across retirement accounts and other index products. Exclusion means those flows do not arrive. For SpaceX, that could leave the stock with a wave of passive demand before most investors have a chance to assess its earnings, ownership structure or long-term profitability.

Control will remain concentrated even if public ownership widens. Musk would hold about 42% of the equity but majority voting power through Class B shares with 10 votes each. A filing provision reviewed by Reuters said he could be removed as CEO and chairman only by a vote of those same Class B holders he controls, making his ouster depend on his own vote. State pension officials from several large public retirement systems are already pressing index providers to justify rule changes that could speed SpaceX’s inclusion.