The Advance-Decline data also known as AD data are calculated to show the number of advancing and declining stocks and traded volume associated with these stocks within a market index, stock market exchange or any basket of stocks with purpose of analysis of the sentiment within the analysed group of stocks. Advance-Decline data are used to measure overall market breadth as well as to measure sentiment within the stock market sectors.
First time Advance-Decline data were calculated and analyzed back in 1926 by Colonel Leonard Ayres, an economist and market analyst at the Cleveland Trust Company. Later James Hughes pioneered the "Market Breadth Statistics". In 1931 Barron's started to publish Advance-Decline numbers. Advance-Decline data analysis remained in shadow until the early 1960s when Richard Russell (Dow Theory) started to use them in his "Dow Theory Letters" and Joseph Granville used them in his "Granville Market Letter".[1]