Interested Shareholder
  
Someone who cares a lot about company success, direction, strategy, tactics. That shareholder is likely interested because they own a ton of shares of the given company. And that influence trickles down throughout the business, as that shareholder has the right to vote those shares in electing the board director they...dig.
And remember: the board hires (and fires) the CEO. So...at the shareholder meeting, you can bet that interested shareholder gets the donut tray with the sprinkles and the glaze.