"BlackRock, itself is also owned by shareholders. Who are those shareholders? We come to a strange conclusion. The biggest shareholder is Vanguard. But now he gets murky. Vanguard is a private company and we cannot see who the shareholders are."
In the bad old days (when coal miners paid in company scrip were laid off until they used it all up at the company store), it was called "interlocking directorships".
It's sort of like the Federal Reserve, whose true owners are a tightly held secret, you could more easily get an accurate account of the scabies on Felonia's PantzSuits.
