The advance-decline ratio compares the number of rising stocks to falling ones each day. Here's how to interpret it, when divergences signal danger, and how to use it alongside other breadth tools.
Every trading day, thousands of stocks go up, down, or sideways. The advance-decline (A/D) ratio is one of the core market breadth indicators: the count of stocks that advanced divided by those that declined. A ratio above 1 means more stocks rose than fell; below 1 means the reverse.
On its own, a single day's A/D reading is just a data point. The power comes from tracking it over time, comparing it to the index, and reading it alongside other breadth metrics.
The basic calculation is straightforward:
A/D Ratio = Advancing stocks ÷ Declining stocks
For example, if 2,500 stocks advanced and 1,000 declined on a given day, the ratio is 2.5. That's a strong breadth day. If only 800 advanced while 2,200 declined, the ratio is 0.36 — a weak, broadly negative tape regardless of where the index closed.
WideRadar tracks the 1-day, 5-day (rolling), and 10-day A/D ratios across the full US universe, applying the same $3 price and 100k average volume filter used for all other breadth metrics. This ensures only liquid, tradeable stocks influence the read.
There are no universal thresholds carved in stone, but these are useful benchmarks:
A single strong day can push a struggling tape's ratio into "healthy" territory — which is why the 5-day and 10-day smoothed ratios are more reliable than the daily figure alone.
The most actionable A/D signals come from divergences — when the index moves in one direction but the breadth ratio moves in another.
Bearish divergence: The index grinds to a new high, but the A/D ratio has been quietly declining over the same period. Fewer stocks are participating in each successive new high. This is a classic warning sign of a narrowing rally that often precedes a reversal.
Bullish divergence: The index is making lower lows, but the A/D ratio has been improving — more stocks are holding up than you'd expect given the index decline. This can signal a coming recovery before the index confirms it.
Divergences rarely give you an exact day to act. They give you a context to operate in: raise cash into bearish divergences, look for entries into bullish ones.
The A/D ratio captures whether more stocks rose than fell — but a stock that gained 0.1% counts the same as one that gained 8%. Combining the A/D ratio with the 4%+ move count gives you a fuller picture:
Both metrics are visible in the WideRadar Breadth tab, updated daily across the full US equity universe.
Sources & References
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