Basically yes. Stocks, shares, and all those things are based on speculation of what the value could be not on what its actual worth is. He is important to apple, not as a person progressing the tech, but as their savior. If you got news that the person, who single handedly saved your company from going under, was now going to be gone, you would be freaking out to. That is why share prices drop. EDIT: http://www.cnn.com/2009/HEALTH/06/24/liver.transplant.priority.lists/index.html So it looks like it was his liver.