Mapping the stock market

Tomalak's realm logged this Mappa.Mundi article on the map that shows "changing stock prices of over 500 publicly-traded companies on a single screen". I remember 2 years ago seeing a building-sized screen billboard covering the J&R Office World's new building that had this graphic on it with Black, Green and Red squares and labels of what seemed like industry sectors. I thought to myself. Hmm. Looks like an information graphic. (I never checked out the URL, though. Can't remember actually seeing one.) It is in fact a great example of how information visualization can help to effiently and quickly communicate what is happening with large data sets -- like money changing hands in the stock market. Here's how it works: In the map each tile represents a single company, with the size of the tile being proportional to its market capitalization. So, the larger the tile, the greater the value of the company. This allows the value of different companies to be assessed by simply comparing the size of their tiles. The colour of the tile encodes the change in the company's stock price over a set time period.