The difficulty with an "assassination market" is that markets facilitate the transmission of information to everyone.<p>Suppose an assassin wishes to purchase futures for, e.g., Obama dead on 5/15. If she purchases more than the normal amount of Dead Obama 5/15 Futures (DO515F), there will be a price impact. All of a sudden, the price of DO515F will spike and an observer will conclude there is an elevated probability of assassination on 5/15.<p>A system designed to disseminate information as widely as possible is not that useful for conspiracies.