advance/decline line (A/D or AD)

A widely used technical indicator that plots the difference between the number of declining issues and advancing issues for a specific period of time (intraday, daily, or weekly). It is calculated by subtracting the declining issues from advancing issues and adding the result to the previous day's number. Technicians use advance/decline line charts as a breadth-of-market indicator to detect early signs of a change in the market bias. See Advance/Decline Ratio.