This has been a thing in the CRSP indexes (ie. the benchmark for Vanguard’s VTI) forever. As long as it meets float and cap requirements, it’s inserted into the indexes five days after trading begins.
It makes sense. They intend to track the market as it is.
Though, you can definitely make the case that the popularization of index funds has allowed their holders to essentially become patsies to hype IPOs.
> This has been a thing in the CRSP indexes (ie. the benchmark for Vanguard’s VTI) forever.
CRSP has recently changed their rules:
> CRSP indexes were also recently changed to better accommodate fast entry. New IPOs are eligible for CRSP's suite of indexes after five trading days, provided they pass the index's eligibility and investability screens. Previously, these screens included having at least 10% of shares qualifying as freely tradeable (known as float shares outstanding, or FSO). However, in April the methodology changed to allow stocks with either 10% FSO or approximately $3.3 billion in float-adjusted market capitalization to be eligible for index inclusion. The weighting of stocks in CRSP indexes is also based on free float, which should help address the investability challenges associated with thinly traded stocks.
* https://www.schwab.com/learn/story/some-indexes-accelerate-e...
> As long as it meets float and cap requirements
Even with the CRSP indexes this was recently changed to make fast-tracking for these IPOs easier.[0]
> CRSP indexes were also recently changed to better accommodate fast entry . . . Previously, these screens included having at least 10% of shares qualifying as freely tradeable (known as float shares outstanding, or FSO). However, in April the methodology changed to allow stocks with either 10% FSO or approximately $3.3 billion in float-adjusted market capitalization to be eligible for index inclusion.
That change is notable because both Anthropic and SpaceX are planning to IPO at well under that old 10% requirement.[1] Neither would have qualified for fast-track inclusion before, but both are virtually guaranteed to clear the absolute valuation bar.
[0]https://www.schwab.com/learn/story/some-indexes-accelerate-e...
[1]https://www.economist.com/finance-and-economics/2026/06/01/c...