Hi everyone, just joined, and posting my first question! I don't understand how the advancing issues and declining issues work, as well as the Adv-Dec differences. Is it just based on volume, or does it mean something else? Any insight would be great, thank you!

The Advance / Decline Line (A/D Line) measures how many stocks are up on the day versus those that are down on the day (as compared to yesterday’s close).

The formula is: Advancing stocks - Declining stocks = Advance / Decline number. The A/D line shows how this number is changing over time.

The S&P 500 A/D Line ranges between +500 (all S&P 500 stocks are up on the day) to -500 (all S&P 500 stocks are down on the day).

The NYSE A/D line can range up to somewhere around +3000 down to -3000. The exact number will change based on how many stocks are currently listed on the NYSE.

There are a few uses of the A/D Line. The one i think is most useful is seeing divergence when compared to /ES and /YM.