Does inclusion in S&P 500 even happen fast enough after IPO to matter here, thought there was usually a wait period before index funds have to buy in?
Frankly, no company should be allowed to IPO without showing steady profit. An exchange or index that promotes IPOs of unprofitable companies diminishes its reputation, and the reputation of all other stocks it indexes.
Anthropic is free to continue selling shares privately. They can setup a website and take cc payments if the care so much.
This is directly counter to the original point of public markets at all