NEW YORK CITY, New York: S&P Dow Jones Indices has decided against changing its rules to allow newly public mega-cap companies to enter its major stock indexes more quickly, preserving requirements that could delay the inclusion of some of the largest upcoming IPOs.

The index provider said that, after reviewing feedback from a broad range of market participants, its index committee opted to maintain the existing eligibility criteria for the S&P 500, S&P MidCap 400, and S&P SmallCap 600 indexes.

Among the current requirements is a rule that companies completing an initial public offering must trade on an eligible exchange for at least 12 months before they can be considered for inclusion in an index.

The committee considered shortening that waiting period to six months, but ultimately decided against making the change.

It also rejected the idea of creating exceptions based solely on a company's market capitalization, a measure of its overall stock market value.

The decision comes as several highly valued technology companies prepare for public listings that could rank among the largest IPOs in history.

Elon Musk's SpaceX is expected to go public this month, planning to raise as much as US$75 billion, a deal that would be the largest stock market debut on record.

Anthropic, the developer of the Claude chatbot, announced plans for a proposed IPO earlier this week, while OpenAI, the maker of ChatGPT, is reportedly targeting a public offering as early as this fall.

Under S&P's current rules, even companies with massive valuations would still need to satisfy the standard waiting period before becoming eligible for inclusion in its flagship indexes.

The move contrasts with a recent policy change by Nasdaq.

In March, Nasdaq introduced guidelines allowing the accelerated addition of large newly public companies to its Nasdaq 100 Index, which tracks the largest non-financial companies listed on the exchange.

Nasdaq said the change was intended to ensure that the index more accurately reflects the market soon after major companies go public, rather than waiting months for their inclusion.

S&P acknowledged that maintaining its current approach may involve trade-offs but said the existing framework continues to provide its indexes with "substantial market coverage and sector balance."

The decision is significant because S&P indexes are widely used by pension funds, mutual funds, and other institutional investors as benchmarks for investment performance.

As a result, inclusion in an index can boost demand for a company's shares from funds that track or seek to mirror those benchmarks.

With several blockbuster AI-related listings expected in the coming months, the debate over how quickly newly public companies should be added to major indexes is likely to remain a focus across Wall Street.