To complete this thread:

“Managers” are controlled by the C-Suite through institutional politics and incentive structures, the C suite (via the CEO) is held accountable by shareholders, and the board (who are theoretically representing shareholder interests).

A rough picture of shareholder concentration is as follows: 50% of stocks and mutual funds are held by the top 1% richest, 87% by the top 10% richest. Vanguard/Blackrock/State Street cast about a quarter of the votes at S&P500 shareholder meetings, ostensibly in the interest of their shareholders.

So that’s who “controls” management, and whose interests drive most corporate decision making, though obviously there are nuances.