They can have big shares in Bitcoin circulating supply but control the network, they won't have that power.
Black Rock started to show something big in the last year by investing in 4 of 5 biggest Bitcoin mining companies.
BlackRock is a major shareholder in 4 of the 5 largest Bitcoin miners. And they also spent their resources for Bitcoin Spot ETF application against SEC. Finally they succeeded and they are buying a lot of bitcoin last 40 days. Already surpassed MicroStrategy as a biggest public company holds Bitcoin.
https://bitcointreasuries.net/
Exactly.
They hold more Bitcoin currently and have the biggest share, I think they can influence bitcoin price but not necessarily the bitcoin network.They only are investing rapidly into the market and thus expanding the bitcoin ecosystem but the bitcoin network is entirely out of the control of anyone or organisation.
Blackrock aim is for profit making not taking over a network that is decentralized.