The S&P 500 already made a big call on SpaceX stock and index fund investors need to know it

Americans have more money invested for retirement in passive S&P 500 Index funds than any other investment. The Vanguard and BlackRock S&P 500 ETFs alone manage nearly $2 trillion in assets, with the Vanguard ETF ( VOO ) recently passing the $1 trillion mark.

But they won't be managing SpaceX shares any time soon for retail investors clammoring to get a piece of the action in Friday's mega-cap IPO , the biggest in the history of the market.

The index committee that oversees the rules for new stock inclusion in the S&P 500 Index said no to the biggest IPO in history, at least for the first year of its public market trading history.

Faced with a new era of mega-cap stocks — with OpenAI and Anthropic expected to follow the SpaceX IPO on Friday with huge offerings pushing them into the territory of the largest publicly traded companies in the U.S. on day one — the index manager was forced to make a call on whether to move up its standard 12-month waiting period for new stocks.

Unlike the S&P, index committees for the Nasdaq and Russell market benchmarks said they would update their rules. In the simplest terms, here's what that means for core U.S. market index fund investors.

"If you want SpaceX, you're not buying the S&P 500. You're going to buy the NASDAQ 100 or the Russell 1000 ," said Strategas Securities chief ETF strategist Todd Sohn on this week's "ETF Edge."

SpaceX is set to begin trading on the Nasdaq Friday, but if you hold an ETF like VOO, or BlackRock's IVV , or the State Street SPDR S&P 500 Trust ( SPY ), you will be waiting for your SpaceX exposure until mid-2027.

The decision to leave in place the long window before SpaceX ever becomes part of the S&P 500 is not one that sat well with Peter Haynes, TD Securities' head of index and market structure research, supported. "Personally, I didn't agree with the decision," he told "ETF Edge."