what is the advance decline a d line 
the advance decline line or a d line is a technical indicator that plots the difference between the number of advancing and declining stocks on a daily basis the indicator is cumulative with a positive number being added to the prior number or if the number is negative it is subtracted from the prior number the a d line is used to show market sentiment as it tells traders whether there are more stocks rising or falling it is used to confirm price trends in major indexes and can also warn of reversals when divergence occurs the formula for advance decline a d line is a d net advances pa if pa value exists0 if no pa valuewhere net advances difference between number of dailyascending and declining stockspa previous advancesprevious advances prior indicator reading begin aligned text a d text net advances begin cases text pa if pa value exists text 0 if no pa value end cases textbf where text net advances text difference between number of daily text ascending and declining stocks text pa text previous advances text previous advances text prior indicator reading end aligned a d net advances pa if pa value exists0 if no pa value where net advances difference between number of dailyascending and declining stockspa previous advancesprevious advances prior indicator reading 