FYI: Technicians typically use market breadth as a tool to confirm the direction of the overall market. When the market is moving higher and breadth is positive, it serves as confirmation of the rally. Conversely, if the market is rallying but breadth is weak, it could spell trouble for the market. One of the most basic ways to measure market breadth is through the cumulative advance/decline (A/D) line. This indicator simply adds the net number of stocks (advancers minus decliners) in an index that traded higher on the day and then adds that number to a running total from a specific starting point.
Regards,
Ted
http://www.bespokeinvest.com/thinkbig/2014/9/16/breadth-by-market-cap.html?printerFriendly=true
