Four banks have custody of over US$179 Trillion in assets
That is not a typo, Trillion. These are a special type of bank called a custodian bank:
BNY Mellon, US$45.3 trillion in assets under custody and/or administration as of September 30, 2021
State Street, US$43.3 trillion in assets under custody as of September 30, 2021
JPMorganChase, $31.3 trillion in assets under custody as of the September 30, 2021
Citibank, over $28 trillion in assets under custody as of 2021
This is the aggregate of assets(in value) managed by mutual funds like BlackRock and Vanguard who are required to hand over custody of the proxy voting rights of stock held in their ETFs to these banks.
In this way, these four banks control the boards of every major publicly traded corporation. And they do it by voting the shares you purchase.
>BNY Mellon, US$45.3 trillion in assets under custody and/or administration as of September 30, 2021
https://www.bnymellon.com/us/en/about-us/newsroom/press-release/bny-mellon-to-speak-at-the-goldman-sachs-2021-us-financial-services-conference-130235.html
>State Street, US$43.3 trillion in assets under custody as of September 30, 2021
https://sec.report/Document/0000093751-21-000691/
>JPMorganChase, $31.3 trillion in assets under custody as of the September 30, 2021
https://www.jpmorganchase.com/content/dam/jpmc/jpmorgan-chase-and-co/investor-relations/documents/quarterly-earnings/2021/3rd-quarter/3Q21-10-Q.pdf
>Citibank, over $28 trillion in assets under custody as of 2021
https://au.finance.yahoo.com/news/citi-securities-services-taskize-partner-090000254.html