Accumulation/Distribution Line

Volume

What it measures

The A/D Line is a cumulative running total, similar in structure to OBV, but instead of using the simple up-day/down-day rule, it weights each bar's volume by where the close landed within that bar's high-low range (the Close-Location Value). A close near the high of the day contributes strongly positive; a close near the low contributes strongly negative — even on a day where the close is only marginally up or down from the prior close.

How readings are interpreted

A rising A/D Line suggests sustained accumulation — buyers pushing closes toward the top of each day's range over time. A falling A/D Line suggests distribution — sellers pushing closes toward the bottom of the range. Divergence between the A/D Line and price (price rises while A/D Line falls) is the classic warning signal that a rally may lack genuine underlying support.

Conventional levels

A/D Line rising with price: accumulation confirms the uptrend
A/D Line falling while price rises (bearish divergence): distribution happening under the surface of an apparently healthy rally
A/D Line rising while price falls (bullish divergence): accumulation happening under the surface of an apparent decline, a classic bottoming signal watched by technicians

Where it works, and where it does not

Works across most conditions since it directly incorporates intrabar price behavior rather than only the day-over-day close comparison OBV uses. Considered by many technicians to be a somewhat more nuanced volume-flow measure than OBV for exactly this reason.

Commonly read alongside

OBV: A related but distinct calculation — when both A/D Line and OBV agree, the volume-flow signal is stronger; when they diverge from each other, worth investigating why
Support/Resistance: A/D Line divergence near a key support or resistance level is more actionable than divergence in open space
Price trend: Primarily useful as a confirmation/warning layer on top of price trend, not as a standalone directional signal

Known limitations

Cumulative and unbounded like OBV and PVT — only trend and divergence matter, never the absolute level or cross-ticker comparison
A single unusual bar (a gap-and-fill day, for instance) can distort the Close-Location Value calculation for that bar
Divergence signals, while a classic technical pattern, don't come with a defined timeframe for when the divergence will resolve

In practice

Use A/D Line divergence from price as an early warning system, the same way you'd use OBV or PVT divergence
Compare against OBV — general agreement between the two increases confidence in the volume-flow read
Best applied to the same ticker's own history over time, never as an absolute cross-ticker comparison
Particularly useful for spotting distribution happening quietly beneath an uptrend that still looks healthy on price alone

Plot it yourself. Add this indicator to a chart, change every parameter and watch the line move, then backtest how the rule would have behaved on historical data — free on the S&P 500 ETF, no card.

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This is reference material, not advice. It describes what each indicator measures and how its readings are conventionally interpreted. Nothing here is a recommendation to buy or sell anything, and no indicator predicts future prices. GU Analyser is an analytical tool — no money is ever traded here.