Stock plunged January 4th, Monday

Evaporation of 2.4% of Dow means that almost 400 billion dollars just evaporated. Had they been real? The question is deeper than one may think. The first part of it is the relation between production of products and services and a stock. Does total value of companies on stock markets represent something real? The second question is trickier: does money represent something real or they are just means to regulate our lives? http://bbc.in/1Z1PCmY via @BBCNews