On-balance volume (OBV) is a technical analysis indicator intended to relate price and volume in the stock market.[1] OBV is based on a cumulative total volume.
OBV=OBVprev+\left\{\begin{matrix} volume&if close>closeprev\\ 0&if close=closeprev\\ -volume&if close<closeprev\end{matrix}\right.
Total volume for each day is assigned a positive or negative value depending on prices being higher or lower that day. A higher close results in the volume for that day to get a positive value, while a lower close results in negative value.[2] So, when prices are going up, OBV should be going up too, and when prices make a new rally high, then OBV should too. If OBV fails to go past its previous rally high, then this is a negative divergence, suggesting a weak move.[3]
The technique, originally called "continuous volume" by Woods and Vignola, was later named "on-balance volume" by Joseph Granville who popularized the technique in his 1963 book Granville's New Key to Stock Market Profits.[4] The index can be applied to stocks individually based upon their daily up or down close, or to the market as a whole, using breadth of market data, i.e. the advance/decline ratio.
OBV is generally used to confirm price moves.[5] The idea is that volume is higher on days where the price move is in the dominant direction, for example in a strong uptrend there is more volume on up days than down days.[6]
Other price × volume indicators: