On-Balance Volume (OBV)

On-balance volume (OBV) is a technical analysis indicator that keeps a running total of trading volume, adding each period's volume when the price closes higher than the previous close and subtracting it when the price closes lower. The resulting line is meant to show whether volume is flowing into or out of an asset, on the idea that changes in volume can come before changes in price.

OBV was introduced by the American market analyst Joseph Granville in his 1963 book on stock market timing, and it remains one of the simplest and most widely available volume indicators on charting platforms for stocks, futures and cryptocurrencies. It belongs to the same family as the accumulation/distribution indicator, the money flow index and the negative volume index, all of which combine price and volume.

Picture a scoreboard at a market stall. Every day the stall's price ends higher, the day's number of trades is added to the score; every day it ends lower, that number is taken away. Over weeks, the score shows whether more trading has happened on rising days or on falling days.

If the score climbs steadily while the price drifts sideways, it suggests buyers are quietly stepping in. If the score falls while the price holds up, it hints that sellers are becoming more active. Traders use OBV to look for these mismatches, not as a precise forecast.

For each new period, OBV is calculated from the previous value:

• $\text{OBV}_t$ is on-balance volume at the end of period $t$, and $\text{OBV}_{t-1}$ is its value for the previous period.
• $V_t$ is the volume traded in period $t$.
• $s_t$ equals 1 if the closing price $C_t$ is above the previous close ($C_t \gt C_{t-1}$), equals −1 if it is below ($C_t \lt C_{t-1}$), and equals 0 if the two closes are the same.

Suppose a token closes at 10.00 on day one, which is taken as the starting point with OBV of zero. Day two closes at 10.40 on volume of 50,000, so OBV becomes 0 + 50,000 = 50,000. Day three closes at 10.10 on volume of 30,000, so OBV falls to 50,000 − 30,000 = 20,000. Day four closes at 10.10 again on volume of 40,000; the price is unchanged, so OBV stays at 20,000. Day five closes at 10.60 on volume of 70,000, taking OBV to 20,000 + 70,000 = 90,000.

The absolute number has no meaning on its own, because it depends on the starting date. What matters is the direction and slope of the line compared with the price.

• Confirming trends. When price and OBV both make higher highs, the rally is said to be supported by volume. A rising price with a flat or falling OBV is treated as a weaker move.
• Spotting divergence. A divergence occurs when OBV and price move in opposite directions. Granville argued that volume tends to lead price, so a rising OBV during a sideways or falling market is read as possible accumulation, and a falling OBV during a rally as possible distribution.
• Breakouts. Some traders watch for OBV to break above its own previous highs before price does, as an early signal.
• Smoothing. Because the raw line is jagged, many apply a moving average to OBV and treat crossovers as signals.

OBV is usually combined with other tools, such as the relative strength index or a candlestick chart, rather than used alone.

OBV is a standard option on crypto charting tools and exchange interfaces. Crypto markets trade around the clock, so the "close" depends on the chart's chosen time frame and time zone, and the same asset can show different OBV lines on different settings. Volume is also split across many venues, and reported volume on some smaller exchanges has historically been inflated by wash trading, which can distort the indicator. Traders therefore often prefer volume from large, reputable venues or aggregated sources when using OBV on tokens.

OBV treats all of a period's volume as buying or selling depending only on the close, so a day that closes one cent higher counts its entire volume as positive, even if most trading happened at lower prices. A single unusual day, such as an index rebalancing or a large block trade, can shift the line for a long time. The indicator says nothing about why volume changed, and like other lagging indicators it can give late or false signals in choppy markets. It is a descriptive tool for reading market behaviour, not a reliable predictor of future prices, and it is no substitute for fundamental analysis or risk management.