Skip to main content

Williams' Accumulation/Distribution (WAD)

Summary

Williams' Accumulation/Distribution: a cumulative line meant to expose whether a security is quietly under accumulation (informed buying) or distribution (informed selling) beneath the surface of price. Larry Williams built it to catch that shift before price confirms it — traders watch for the line to diverge from price, since a line that keeps rising while price stalls or falls points to accumulation, and one that stalls while price pushes to a new high points to distribution.

It consumes no volume. Larry Williams' original multiplies each move by that bar's volume; Steven Achelis published the modification that drops the multiplier (Technical Analysis from A to Z, 2nd ed., p.368), and the industry kept Williams' name on that no-volume form. That industry-wide decision is enough for TA-Lib to ship the same form under the same name. What remains once the multiplier is dropped is a signed close-to-close move measured on the true range, so it is grouped as a momentum indicator, not a volume one.

Formula

For each bar t:

TRH_t = max(close_{t-1}, high_t)
TRL_t = min(close_{t-1}, low_t)

if close_t > close_{t-1} then AD_t = close_t - TRL_t
if close_t < close_{t-1} then AD_t = close_t - TRH_t
otherwise                     AD_t = 0

WAD_t = WAD_{t-1} + AD_t

The first bar of the requested range has no previous close, so the first output is always AD_t = 0. A different startIdx shifts WAD's whole line by a constant.

Inputs

  • inHigh — High price of each bar
  • inLow — Low price of each bar
  • inClose — Close price of each bar

Outputs

  • outReal — Cumulative accumulation/distribution

Properties

Numerical Stability: Path-Dependent

☐ Overlap Input
✅ Independent Y-Axis i
☐ Candlestick
☐ Can Output NaN or ±Inf
☐ Identity at Period 1

Implementation

TA-Lib Definition: wad.c · wad.yaml

NativeFile
Cta_WAD.c
Rustwad.rs
JavaCore_WAD.java
C#Core_WAD.cs

TA-Lib is also available for Python, R and more using a wrapper.

See Also

AD · ADOSC · NVI · OBV · PVI

References

  • Larry Williams is the originator; Steven Achelis, Technical Analysis from A to Z, 2nd edition, page 368 publishes the no-volume form this ships, with the worked 12-bar example pinned in the test suite.
  • IncredibleCharts, Williams Accumulation Distribution — Williams' volume-weighted original, AD = Price Move × Volume over the same true-range price move.
  • IncredibleCharts, Williams Accumulate Distribute — the Achelis form under its disambiguating name, "not a volume indicator despite the name".
Last Updated: