link to archived Reddit thread; original post removed/deleted
Not really, no. This is mostly a myth. Unless the executives are deliberately causing the company to lose money, they really can't be sued based on this fiduciary duty to shareholders. They have to act in the shareholders' best interest, but "shareholder interest" is entirely up to interpretation. For example, it's perfectly fine to say, "we're going to lose money over the next five years because we believe it will ensure maximum profits over the long term." In order to sue a CEO for failing to protect shareholders, they would have to be doing something deliberately and undeniably against shareholder interest. Like if they embezzle money into their own bank account, or if they hold a Joker-style literal money burning.
If it were that easy to sue executives for violating their fiduciary duty to shareholders, golden parachutes and inflated executive compensation packages wouldn't exist. But good luck suing a CEO because he's paid too much. He can just claim in court that his compensation will ensure the company attracts the best talent to perform the best they can.
Executives are given wide latitude in how they define the best financial interest of shareholders. Shareholders ultimately do have the ability to remove executives from their positions. This is supposed to be the default way of dealing with incompetent executives. As shareholders already possess the ability to fire a CEO at any time, there is a very high bar to clear before shareholders can also sue executives. It's generally assumed if they really are doing that bad a job, you should just fire them.