Do Investors Care if Steve Jobs is Healthy?

Steve Jobs of Apple, Inc., is one of the best known CEOs in the world and some stock analysts have termed him “irreplaceable.”  Using conventional event study methods, we test whether announcements concerning his health have a statistically significant influence upon Apple’s share prices.  We focus upon nine “events” between 2004 and 2009 in which new information about Mr. Jobs’ health was flushed into the marketplace, on occasion by Apple itself, but more often by the commentary and speculations of media observers, stock analysts and bloggers.  We find that the impact of these announcements upon Apple share prices is mixed, usually modest, and disappears over time.  We conclude that many investors do pay attention to Jobs’ health, but not nearly as much as many observers apparently believe.