Popular Science Preictions Exchange (PPX) is a online virtual Prediction market run as part of the Popular Science Magazine website. The application was designed by the same group behind the Hollywood Stock Exchange using their Virtual Specialist Application. Users trade virtual currency, known as POP$, based on the likelihood of a certain event being realized by a given date. Stock prices range between POP$0 and POP$100 and are intended to reflect the general confidence of the users about that event. A stock at price POP$95 would mean roughly that users believe there to be a 95% chance of the event happening. Should an event be realized by the given date, the stock will pay out POP$100 per share. A stock that does not occur by the closing date will be worth POP$0 per share.