Williams Accumulation Distribution   

Williams Accumulation Distribution was created by Larry Williams. It is a volume weighted price momentum indicator. It measures buying and selling pressure by calculating the relationship between the numbers of points that the market has moved from open to close, relative to the period’s entire range. Williams Accumulation-Distribution tracks the buying pressure and selling pressure. Williams AD is a running sum of positive accumulation values (buying pressure) and negative distribution values (selling pressure).
Usage:
The Williams Accumulation/Distribution Indicator tries to find underlying relationships between the close, high and low prices. It tracks the buying pressure and selling pressure.
Williams Accumulation-Distribution (WAD) tracks buying pressure (accumulation) and selling pressure (distribution) on a security.
With accumulation, most of the volume is associated with upward price movement.
With distribution, most of the volume is associated with downward price movement.