In US corporate law, a board of directors are elected by the shareholders to represent their interests. The shareholders overriding interest is maximising return on investment.
The extent of US corporate law is that directors have a fiduciary-like duty to maximize shareholder _value_, but also that they must act in the best interests of the company. Statements beyond that are not reflections of law, but of faith.
A couple salient points:
The "best interests of the company" need not, and often are not, simply maximizing quarterly profits, share price, etc. Indeed, sometimes these things are odds with one another.
Moreover, shareholder value includes but is not limited to return on investment. It is simply most convenient _from a managerial perspective_ to simplify diverse shareholder notions of value down to the most legible lowest common denominator.
The folks who are downvoting you need to google "board of directors liability". If the Board doesn't act in the benefit of shareholders, they'll get sued to oblivion.
