> Shareholder primacy was famously established in the decision of Dodge v. Ford Motor Co. in 1919. In Dodge v. Ford Motor Co.'s court opinion, it stated that "there should be no confusion" that "a business corporation is organized and carried on primarily for the profit of the stockholders." Because of this opinion, a precedent was set that managers had to maximize shareholder profit.
https://en.wikipedia.org/wiki/Shareholder_primacy