The Accumulation/Distribution Rating® tracks the relative degree of institutional buying (accumulation) and selling (distribution) in a particular stock over the last 13 weeks.
Updated daily, stocks are rated on an A to E scale:
A = Heavy buying
B = Moderate buying
C = Roughly equal amount of buying & selling
D = Moderate selling
E = Heavy selling
There are two proprietary adjustments. The daily A-E rating is adjusted for the percent change in the close relative to the stock's/index's trading range. Also, any unusual spikes in volume caused by offerings or other irregular circumstances are eliminated to smooth the data and avoid distortions.