almost all 401k plans offer funds based on s&p 500, not nasdaq/russell others. s&p has also halved their trading days requirement from 1 yr to 6 months, but that's still sufficient to be past the post-ipo lock-up period.

I don't think the S&P has actually made a decision yet. It is in progress, though: "The S&P Index Consultation on MegaCap IPOs" is the search term

What is being considered by S&P:

> Stocks would become eligible for the index after six months rather than 12 months. The requirement to have a minimum Investable Weight Factor of 0.10 (roughly at least 10% of shares publicly floated) would be dropped. Companies would not be required to demonstrate profitability.

* https://www.schwab.com/learn/story/some-indexes-accelerate-e...

Though:

> Still, S&P Dow Jones reminds market participants that the proposed changes would apply only to index eligibility. The actual inclusion of new constituents remains entirely at the discretion of the index committee.

sp500 has profitability requirement, I doubt LLM companies will show profits any time soon.