Adds analyst comment in paragraphs 5-6, details throughout

By Pritam Biswas and Noel Randewich

June 4 (Reuters) - S&P Global SPGI.N said on Thursday it was not changing the rules for fast entry into their major indices, dealing a setback to Elon Musk's SpaceX by effectively ruling out a swift entry into the benchmark S&P 500.

Musk has rewritten the IPO playbook for ⁠SpaceX in many ways from planning to give retail investors a bigger role in allocations to pushing for early index inclusion, and structuring governance to preserve strong founder ​control.

S&P said "exceptions to the financial viability, seasoning, and IWF (investible weight factor) requirements should not be granted solely based on market capitalization".

SpaceX is aiming to raise $75 billion, the biggest ever for an IPO, in a ​deal that would value it at $1.75 trillion, immediately placing it among the top 10 most valuable U.S.-listed firms.

"It speaks highly of the credibility of S&P Dow Jones Indices to be rules-based and make sure there's profitability before the entrance to index," said Art Hogan, Chief Mark at Strategist at B. Riley Wealth.

"Making exceptions because companies are so large and have been private so long yet are still not profitable, didn't make a great deal of sense."

Exchange operators have ramped up efforts to boost initial public listings as richly valued technology firms such as SpaceX and AI giant Anthropic edge closer to public offerings, amid growing concerns over a steady decline in the number of U.S.-listed companies.

Rapid index inclusion post-IPO boosts liquidity and visibility, attracting passive investment inflows. This automatic demand stabilizes share prices.

SpaceX has already become eligible for inclusion in both the Russell U.S. Equity Indexes and the FTSE Global Equity Index Series under the newly announced fast-entry rules from the index provider FTSE Russell.

But for the S&P indices, IPOs need to be traded on an eligible exchange for at least 12 months before being considered for an addition to an index such as the S&P 500 .SPX.