Direct Answer
Wilder's relative strength index calculated on a breadth series, such as the advance-decline line, instead of on price. It converts average gains and average losses in breadth into a bounded 0 to 100 oscillator. Readings above 50 mean gains in breadth have outweighed losses over the lookback.
Breadth RSI: Formula, Meaning, Signals, Examples and How to Use It
How Is Breadth RSI Calculated?
Wilder's relative strength index calculated on a breadth series, such as the advance-decline line, instead of on price. It converts average gains and average losses in breadth into a bounded 0 to 100 oscillator.
Formula: RSI = 100 - 100 / (1 + RS), where RS = average gain / average loss of the breadth series over N periods
Inputs:
- A breadth series such as the cumulative advance-decline line
- Lookback length N, commonly 14
- Average gain and average loss over the lookback
Worked example. If the average one-period gain in the breadth series is 0.8 and the average loss is 0.4, the RSI is 66.7. The inputs are illustrative numbers, not market data.
Reading it. Readings above 50 mean gains in breadth have outweighed losses over the lookback. The 70 and 30 levels carry over from price RSI as conventional overbought and oversold markers, but for breadth they only describe how stretched breadth momentum is.
Limits. Breadth lines are cumulative and can trend for long periods, so RSI can stay in its extreme zones. The conventional 14-period and 70/30 settings were designed for price, not breadth.
What is Breadth RSI?
Wilder's relative strength index calculated on a breadth series, such as the advance-decline line, instead of on price. It converts average gains and average losses in breadth into a bounded 0 to 100 oscillator.
How to use Breadth RSI
Readings above 50 mean gains in breadth have outweighed losses over the lookback. The 70 and 30 levels carry over from price RSI as conventional overbought and oversold markers, but for breadth they only describe how stretched breadth momentum is. A reading alone is never a buy or sell signal; it needs context from price structure, volume, volatility and the broader market regime.
Strengths
- Wilder's gain-and-loss averaging converts an unbounded breadth line into a 0 to 100 scale, giving fixed reference levels for comparing very different periods.
- It uses the ratio of average up-changes to average down-changes, so it responds to the consistency of breadth improvement and not only its level.
- Reproducible when the formula and data convention are fixed.
Weaknesses and limitations
- When the average loss over the lookback is near zero the RS term explodes, pinning the reading near 100 until losses appear again.
- Wilder smoothing keeps old observations in the averages at small weights indefinitely, so the reading depends on how far back the series was started.
- Correlated indicators can create false confidence by repeating the same underlying information.
Editorial and risk note
This page is educational content, not individualized investment advice. It should not imply guaranteed prediction, accuracy or outperformance.
Frequently Asked Questions
Is Breadth RSI a buy or sell signal?
No. Readings above 50 mean gains in breadth have outweighed losses over the lookback. Breadth lines are cumulative and can trend for long periods, so RSI can stay in its extreme zones. A trade built on it still needs a trigger, an invalidation rule, a position size and realistic execution assumptions.
What is the best setting for Breadth RSI?
Breadth RSI takes these inputs: a breadth series such as the cumulative advance-decline line; lookback length N, commonly 14; average gain and average loss over the lookback. There is no universal best setting for the tunable ones, so test them across instruments, regimes and out-of-sample periods and favor stable parameter regions over one historical winner.
Can Breadth RSI be used by itself?
Breadth lines are cumulative and can trend for long periods, so RSI can stay in its extreme zones. The conventional 14-period and 70/30 settings were designed for price, not breadth. For that reason it is read next to measures of direction, participation, valuation, liquidity and risk, not alone.
Does Breadth RSI work on every timeframe?
The calculation (RSI = 100 - 100 / (1 + RS), where RS = average gain / average loss of the breadth series over N periods) can be run on any bar size, but behavior is not portable: a reading on a five-minute chart describes a very different market window from the same reading on a daily chart. Validate the exact timeframe before relying on it.
Why does Breadth RSI give false signals?
When the average loss over the lookback is near zero the RS term explodes, pinning the reading near 100 until losses appear again. Wilder smoothing keeps old observations in the averages at small weights indefinitely, so the reading depends on how far back the series was started. Lag, noise and regime changes add to this, because market participants react to new information after the reading is calculated.
How should Breadth RSI be backtested?
Rebuild Breadth RSI from a breadth series such as the cumulative advance-decline line using point-in-time data, write the rules before testing, include delisted securities where relevant, model realistic fills and costs, reserve a validation sample and compare with a simpler baseline.