It's really no mystery - go to Yahoo Finance and look at any big company, look for the "Holders" and inevitably it is Black Rock, Vanguard and State Street as the major holders: https://finance.yahoo.com/quote/RTX/holders?p=RTX

Then you look up say, State Street, and Vanguard and Black Rock control the biggest share: https://finance.yahoo.com/quote/RTX/holders?p=RTX

So they own the biggest fraction, of the biggest fraction, of the biggest fraction, etc........ of just about any significant company.

This was written about in an article I read in the last couple years on a substack somewhere, but I cant find it again off hand.