Accumulation/Distribution Line

Introduction

The OBV lesson built a cumulative volume line using a simple rule: was the close up or down? The Accumulation/Distribution (A/D) Line, developed by Marc Chaikin, refines that idea with a more discerning question: where within each bar did price close? A bar that closes near its high is treated as strong accumulation; one that closes near its low, as distribution; one that closes mid-range counts only partially. Weighting each bar's volume by that position and accumulating it produces a line that, like OBV, reveals whether an asset is being accumulated or distributed over time — but with more nuance about each bar. This lesson explains how the A/D Line works and how it sits between OBV and Chaikin Money Flow.

This builds on the volume, OBV and Chaikin Money Flow lessons — the A/D Line is the cumulative cousin of CMF and the more nuanced cousin of OBV.

Quick Definition

The Accumulation/Distribution (A/D) Line is a cumulative volume-flow line in which each bar's volume is weighted by where the close fell within its high-low range before being added to a running total. A rising A/D Line signals accumulation (net buying flow); a falling one signals distribution (net selling flow). As with OBV, you read its direction and divergence from price, not its absolute value.

The essence: it's a volume line that gives each bar partial credit based on its close. A close right at the high is full accumulation; right at the low, full distribution; in the middle, roughly neutral.

How It Works (and How It Differs from OBV)

The A/D Line uses the same money-flow multiplier as Chaikin Money Flow — where the close sits in the bar's range, from +1 (at the high) to -1 (at the low) — multiplied by the bar's volume, and then accumulated into a running line.

The contrast with OBV is the key insight:

• OBV is all-or-nothing: if the bar closed up, it adds the entire volume; if down, it subtracts the entire volume. The close's position is ignored.
• A/D is proportional: a bar closing near its high adds most of its volume; one closing mid-range adds only a little; one closing near its low subtracts. The close's position is everything.

So a day that gaps up but closes weakly near its low would add volume in OBV (it closed up... or down vs prior) but would register as distribution in A/D (closed near the low). A/D's extra nuance can reveal selling pressure that OBV's blunt up/down rule misses.

Reading the A/D Line

You read the A/D Line just as you read OBV — by direction and divergence, never by its arbitrary value:

• Rising A/D → accumulation: net buying flow supports the price; a healthy uptrend has a rising A/D.
• Falling A/D → distribution: net selling flow; a healthy downtrend has a falling A/D.
• Confirmation: A/D trending the same way as price reassures that volume flow backs the move.
• Divergence: price extending while A/D doesn't — a new high on a lower A/D high (bearish) or a new low on a higher A/D low (bullish) — warns the move lacks volume support and may reverse.

A/D Line versus CMF

The relationship to Chaikin Money Flow is worth making explicit, since they share a building block: CMF is essentially the A/D concept measured over a fixed window as a zero-centred oscillator. The A/D Line accumulates the money-flow volume into an ever-running trend line; CMF averages it over a window (e.g. 20-21 bars) into a bounded oscillator around zero. So:

• Use the A/D Line when you want a long-running accumulation/distribution trend to compare against price (like a more nuanced OBV).
• Use CMF when you want a recent buying/selling-pressure gauge with a clear zero line.

They're two views of the same underlying flow — one cumulative, one windowed.

Common Misconceptions

• "A/D and OBV are the same." OBV counts the whole bar's volume by up/down close; A/D weights it by the close's position in the range. A/D is the more granular of the two.
• "The A/D value matters." It's a cumulative total from an arbitrary start — only its direction and divergence matter, like OBV.
• "A/D and CMF are different indicators with nothing in common." They share the same money-flow building block — A/D is the cumulative line, CMF the windowed oscillator.
• "Rising price always means accumulation." Not if A/D diverges. A rising price with a falling A/D Line signals distribution beneath the surface.

Real-World Application

A trader compares OBV and the A/D Line on a stock making new highs. OBV looks fine — it's rising, because the closes are (barely) up. But the A/D Line is flattening and turning down, because those up-closes are happening near the lows of their ranges — the bars are finishing weakly despite green closes. A/D's range-weighting exposes the distribution OBV's blunt up/down rule misses. Reading the A/D divergence as a warning that sellers are quietly unloading into the highs, they tighten stops and reduce exposure. The stock soon rolls over. They later cross-check the recent pressure with CMF (the windowed version), which has dipped below zero, confirming the shift. A second trader, on OBV alone, saw nothing wrong and held into the decline. The A/D Line's nuance — where in the range price closed — revealed the selling that a cruder volume line concealed.

Key Takeaways

• The Accumulation/Distribution (A/D) Line is a cumulative volume-flow line weighting each bar by where the close fell in its range.
• It differs from OBV by being proportional (close position) rather than all-or-nothing (up/down) — more nuanced about each bar.
• Rising = accumulation, falling = distribution; read direction and divergence, not the arbitrary value.
• It relates to CMF as the cumulative line to CMF's windowed zero-centred oscillator — same flow, two views.
• A/D divergence (price up, A/D down) exposes distribution beneath a rising price that OBV can miss.