The highly anticipated SpaceX IPO could become one of the most valuable public offerings of all time, prompting S&P Global to change its ETF allocation rules. That kind of move has one market expert pushing back.SpaceX Could Break S&P 500 PrecedentSpaceX, led by billionaire CEO Elon Musk, boasts a valuation ranging between $1.5 trillion and $1.75 trillion. It’s targeting an initial public offering on June 12. This valuation would make the space company one of the most valuable in the world and put pressure on the largest stock market indices to include shares alongside the likes of the other top valued global companies.Freedom Capital Markets Chief Market Strategist Jay Woods, who has spent more than 25 years working on Wall Street, argues that SpaceX should get "no fast pass" or "express ticket" to inclusion in the S&P 500 or Nasdaq 100.Woods wrote in a weekly newsletter that he sent an official comment letter to S&P Global, the company behind the S&P 500 Index.To qualify for inclusion in the S&P 500, tracked by the SPDR S&P 500 ETF Trust (NYSE:SPY), companies must:

U.S.-listed stock

Market capitalization of $20.5 billion or more

Have positive reported GAAP earnings in most recent quarter and trailing four quarters combined