Glossary term
Advance/Decline Ratio
The advance/decline ratio compares the number of advancing securities with the number of declining securities in a market or index.
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What Is the Advance/Decline Ratio?
The advance/decline ratio compares the number of securities that rose in price with the number that fell over the same period. It is a market breadth measure, meaning it helps show whether a market move is broadly supported or concentrated in a smaller group of names.
The ratio is usually calculated for a stock exchange, index, sector, or watchlist. A ratio above 1 means more securities advanced than declined. A ratio below 1 means more securities declined than advanced.
Key Takeaways
- The advance/decline ratio divides advancing issues by declining issues.
- It is a simple breadth measure used to read participation in a market move.
- A high ratio points to broad buying pressure; a low ratio points to broad selling pressure.
- The ratio is easier to read for a single day than the cumulative A/D line.
- It can be noisy and should be interpreted alongside price, volume, and the market universe used.
Basic Formula
The standard version is straightforward:
Advancing issues are securities that closed higher than the prior period. Declining issues are securities that closed lower. Some data vendors also track unchanged issues separately rather than including them in either side.
If 1,800 stocks advance and 900 decline, the ratio is 2.0. That means advancing stocks outnumbered declining stocks by two to one. If 700 advance and 1,400 decline, the ratio is 0.5, showing that decliners outnumbered advancers by two to one.
How to Read the Number
The ratio gives a quick snapshot of participation. A market index that rises on an advance/decline ratio of 2.5 looks different from an index that rises on a ratio of 0.8. In the first case, many stocks are moving higher. In the second, a few large companies may be lifting the index while most names are weak.
Investors often use the ratio to confirm or question short-term market moves. It can also help compare sectors. If technology has a strong ratio while financials have a weak ratio, the market's internal leadership may be narrower than the headline index suggests.
Ratio Versus A/D Line
The advance/decline ratio and advance/decline line use similar inputs but answer different questions. The ratio is a period-by-period comparison. The A/D line is cumulative, adding net advances over time.
That distinction matters. The ratio can show a sharp one-day breadth surge or selloff. The A/D line can show whether breadth has been strengthening or weakening over weeks and months. Many market technicians use both: the ratio for daily intensity and the line for trend confirmation.
What to Watch
The ratio can be distorted when the number of declining issues is very small, when the market universe is narrow, or when many securities are thinly traded. It also says nothing about the size of each move. A stock up 0.1% and a stock up 10% both count as one advancing issue.
For that reason, the ratio works best as context. It should be read with price trend, volume, sector leadership, and the composition of the index or exchange being measured.
The Bottom Line
The advance/decline ratio is a quick way to judge market breadth. It helps readers see whether buying or selling pressure is widespread, but it does not replace deeper analysis of trend quality, valuation, risk, or portfolio exposure.