On-Balance Volume
Volume with a direction attached.
Price stalls, but volume keeps flowing in OBV rising while price drifts OBV adds the day's volume when price closes up and subtracts it when price closes down, keeping a running total. The absolute number is meaningless. The direction of the line is the point. OBV rising with price The move has participation behind it. OBV flat while price rises The rise is happening on thin volume. Fewer people are buying it than the price implies. OBV rising while price is flat Accumulation. Someone is buying without pushing the price. Often the most interesting reading. OBV falling while price rises Distribution into strength. A warning. OBV's whole value is divergence. Price is what people paid; OBV is a crude measure of how many of them there were. When those two disagree, the disagreement is the signal.
Part of Learn NEPSE Investing, a free course on reading Nepali company accounts and charts. Section: Charts.