On-Balance Volume - OBV

A method used in technical analysis to detect momentum, the calculation of which relates volume to price change. OBV provides a running total of volume and shows whether this volume is flowing in or out of a given security. This indicator was developed by Joe Granville.

Investopedia Says:
OBV attempts to detect when a financial instrument (stock, bond, etc.) is being accumulated by a large number of buyers or sold by many sellers. Traders will use an upward sloping OBV to confirm an uptrend, while a downward sloping OBV is used to confirm a downtrend. Finding a downward sloping OBV while the price of an asset is trending upward can be used to suggest that the "smart" traders are starting to exit their positions and that a shift in trend may be coming.

Related Links:
Learn about the momentum indicator that its creator described as "a spring being wound tightly". Introduction to On-Balance Volume
Discover the indicators that measure the force of the bulls and bears, telling you what a simple price chart cannot. Market Breadth: A Directory Of Internal Indicators