Advance-⁠Decline Line

What is the Advance-Decline Line?

The Advance-Decline Line is a market breadth indicator that adds each period’s advancing-member count minus its declining-member count to a running total. A security contributes one direction count per observation, regardless of its market capitalization or return size, so the line shows how broadly a market takes part in a rise or a fall.

Define the universe and the comparison period. This example classifies each session’s close against the prior session’s close.

Advance-Decline Line example: 11 sessions from a zero baseline

The chart begins at a zero baseline and shows 11 completed sessions after it. Its daily changes are +140, +115, +65, −30, +55, −45, −90, −55, −75, −60 and −90.

The cumulative line reaches +345 after session 5 and ends at −70. Each point after the baseline adds that session’s advancers minus decliners to the prior reading.

Starting the same sequence at 12,400 produces a final 12,330. Adding a constant shifts the levels while preserving all changes and relative highs and lows.

How a daily Advance-Decline Line updates intraday

A daily A/D preview equals the prior completed daily value plus the current session’s advancing-minus-declining count. Recalculate that provisional addition as prices change.

With a prior 12,400 and current net +140, the preview reads 12,540 on every refresh while the counts hold, and today enters the daily line once, at the close.

To track breadth through the session, build an intraday A/D line that adds net advances bar by bar, with each bar’s reference price and interval set before the open.

How traders use the Advance-Decline Line

Use the member set eligible on each date. To compare groups of different sizes, scale each period’s net advances to 100 × (advances − declines) / eligible members and accumulate those steps; the line then reads net advances per 100 members.

Compare the index and cumulative line at matching highs or lows. A higher breadth low under a lower index low points to a narrowing decline, and today’s advance and decline counts show whether the improvement held this session.

Use absolute changes in the cumulative line when measuring its recent movement. A percentage return on its arbitrary starting level changes when the seed changes.

Use Market Breadth to find the group carrying the move. Options Flow then shows the large orders in that group’s names, and the Options Profit Calculator prices the ticker or index structure at your target.

Limitations of the Advance-Decline Line

• Every member counts the same, so a small gain in a minor stock offsets a decline in the largest index member. Check the index’s heaviest weights before reading a strong line as a strong index.
• Read changes, slope and matched highs or lows. The starting level is arbitrary: the same eleven sessions end at −70 from a zero baseline and at 12,330 from 12,400, so a percentage change in the level moves with the seed.
• Match the universe, historical membership, daily cutoff, price adjustments and initial value before comparing two A/D lines; each one changes the readings.
• Treat today’s point as provisional until the close. The 12,540 preview moves with every change in the session’s counts.
• A divergence measures cumulative participation. The entry and the stop come from the index’s own price levels.

Bottom line

The Advance-Decline Line keeps a running total of advancing minus declining securities, which shows whether a move in an index is broad or narrow. Read its slope and matched highs and lows against the index, keep the universe and cutoff the same throughout, and define the trade with separate price levels.