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Comment by PNewling | Hacker News Reader

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PNewling·

> The S&P 500 does not add companies to its index until at least 12 months after IPO.

Unless you're SpaceX [0], then the rules have exceptions...

[0] https://finance.yahoo.com/markets/stocks/articles/elon-musks...

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Markets can and do change rules from time to time. This rule change would apply to any new listing, not just SpaceX.

Yes, but it was done for spacex and it’s crooked

Why is it crooked? Do you understand why the rules are being changed?

I’m not sure what the justification is, but I assume it’s some flavor of “so index fund holders don’t miss out on returns”. It’s crooked because index inclusion drives massive flows at any price. SpaceX understands this and with so much money on the table probably exerted influence (maybe the big AI players contributed too). Passive funds don’t care about price (quite the opposite, they reward higher market caps in a feedback loop). But with an IPO, you’re supposed to let the market have some time to find the right price. Not to mention the changes related to profitability rules etc.

Agree with this sentiment. However, I think the S&P 500 fudged the rule to 6 months which I believe adequately straddles the line between 1. provides time for price discovery and 2. includes a large piece of the market that would otherwise be included if not for the seasoning cutoff.

Agree with you entirely with respect to other indexes including earlier than 6 months.

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