* Rules aim to boost IPO pipeline ahead of blockbuster

debuts of SpaceX and OpenAI

* Nasdaq seeks to address long waits for large caps to

join benchmark

* Rules to take effect May 1, likely affect index makeup

in June

* Changes include new market-cap calculation method,

removal of 10% float rule

By Anirban Sen and Arasu Kannagi Basil

NEW YORK, March 30 (Reuters) - Nasdaq will roll

out a set of rules including steps to speed up the entry of

newly listed large-cap companies to its Nasdaq-100 index, as the

exchange operator seeks to reduce delays in joining the flagship

equity benchmark.

As richly valued technology companies such as SpaceX and

OpenAI prepare to go public, exchange operators are seeking to

turbocharge the pipeline of initial public offerings amid

concerns over a rapidly shrinking number of publicly listed

companies in the U.S.

Onerous disclosure requirements and the costs of being

publicly listed have also made it less attractive for companies

to seek public markets, with several large startups like Stripe

and Databricks choosing to remain private for longer than

startups typically do.

DWINDLING NUMBER OF PUBLICLY TRADED FIRMS

Nasdaq is looking to revamp its rules to ensure that newly

public large-cap companies and exchange transfers do not face a

long waiting period - potentially up to a year or longer -

before joining the Nasdaq-100, Cameron Lilja, Nasdaq's global

head of index solutions, told Reuters.

"It is not necessarily representative to have a company

that's big and could have a sizable representation in the index

to keep them out for that long," Lilja said in an interview.

"We're seeing share and corporate structures change - and

companies that are staying private considerably longer are thus

growing to be truly mega-cap companies before they even come to

the public markets."

The new rules for Nasdaq-100, including the "fast entry"

provision, will take effect on May 1, though most updates are

not expected to affect the benchmark's composition until June,

Nasdaq said.

The number of public companies listed on U.S. exchanges has

shrunk by more than a third since 2000, according to a white

paper from Nasdaq last year.

The Nasdaq-100 is home to some of the world's largest

publicly traded names, including mega-cap tech stocks Nvidia ( NVDA )

, Apple ( AAPL ) and Amazon.com ( AMZN ). Last year,

Walmart switched its listing to Nasdaq, marking the biggest

exchange transfer ever.

Under the fast-entry rule, Nasdaq will evaluate newly listed

stocks for potential entry by ranking their market

capitalization on the seventh trading day and assessing whether

they would rank within the top 40 index members. If a company

meets all the eligibility criteria, it will be fast-tracked into

the Nasdaq-100 after the 15th day of trading.

Under existing rules, Nasdaq reviews the rankings of index

components only once a year. In a process that can take up to a

year, or even longer, newly public companies must demonstrate

they are stable enough to handle the volume of buy orders from

institutional investors.

Admission to a blue-chip index like the Nasdaq-100 or the

S&P 500 is highly attractive to large-cap companies, as it

​increases their access to the deep-pocketed ​institutional

investors who typically buy sizable positions for their index

funds, broadening the companies' shareholder base and improving

liquidity over time.

Other indexes, including the FTSE Russell and the NYSE 100,

are also racing to introduce major changes to rules governing

the entry of companies into benchmark indexes, as high-profile

names including billionaire Elon Musk's rocket-and-satellite

maker SpaceX, and AI market leaders Anthropic and OpenAI,

prepare for their stock market debuts.

SpaceX is seeking early inclusion to top benchmark indices

including the Nasdaq-100, Reuters reported this month.

NEW RULES

Here are the other rule changes for the Nasdaq-100:

* A new method to calculate the market capitalization of

companies to determine their eligibility for inclusion in the

index. It involves adding listed stock and unlisted shares that

are part of different share classes.

* Scrapping a rule that requires companies to float a

minimum 10% of their shares.

* Companies with a low float will receive a lower weighting

on the index.

* If a company finishes two consecutive months below 10

basis points in weight within the index, it will be removed and

replaced by the next-largest eligible company.

* Updates on total outstanding shares of companies to come

quarterly, replacing the current ad-hoc rule.