Advance / Decline indicators are used to measure market breadth - how the set of market issues contributed to the market’s up or downward movements. There are several different Advance / Decline indicators that utilize the number of advancing, declining, and unchanged issues and sometimes market volume numbers. Generally this information is quoted for an exchange such as the AMEX, NYSE, or Nasdaq.
The Advance-Decline Line is calculated by dividing the number advancing issues by the number of declining issues.
