Earlier quoted context omitted.
If Musk's pressure had succeeded and the S&P and CRSP had changed their index rules, then the major indexes would have been legally obligated to buy SpaceX at the IPO price - or presumably higher because their own mass purchases would have driven the price even higher. That was Musk's plan. It failed because he couldn't get the major indexes to cow tail to his pressure and demands. Edit: My reference to the SEC is th…
You seem to be confused about how index funds work. Hypothetically even if $SPCX was added to the S&P500, funds that track that index wouldn't be legally required to purchase it at the IPO price. Have you ever even read a fund prospectus or do you believe the uninformed nonsense you read online? The way it actually works is that when a stock is added to an index the index funds gradually build a position using a seri…
That means Vanguard VTI tracks the stocks that are contained in the CRSP US Total Market Index. So, if CRSP adds a new holding to its US Total Market Index, Vanguard VTI is legally bound by its prospectus to add that stock to VTI and to do so in a manner that assures VTI returns track the CRSP US Total Market Index returns as closely as possible (meaning they own every stock CRSP does and in the same proportion that CRSP does).
This is not just a 'good idea'. It is legally binding upon Vanguard by virtue of the VTI prospectus.