What is on-balance volume (OBV)?
The indicator was developed by stock market analyst Joseph Granville, who published it in 1963 in his book 'Granville's New Key to Stock Market Profits'. Granville believed that volume was the driving force behind market moves, and that price was merely the effect of volume. When price and OBV move in the same direction, it confirms the current trend. When they diverge, it signals that the trend may be losing momentum.
Grenville was one of the most prominent stock market forecasters of the 1970s and early 1980s. A single telephone hotline recommendation from Granville in January 1981 was reported to have moved markets noticeably, illustrating the influence of volume-based analysis at the time. His key insight, that volume is the fuel that drives the price engine, remains the conceptual foundation of OBV and other volume-based indicators used in modern technical analysis.
How is OBV calculated?
The OBV formula is straightforward. On each trading day:
If today's closing price is higher than yesterday's: OBV = previous OBV + today's volume
If today's closing price is lower than yesterday's: OBV = previous OBV - today's volume
If today's closing price equals yesterday's: OBV = previous OBV (unchanged)
An example:Day 1: stock closes at 500p, volume 20,000. Starting OBV = 20,000.
Day 2: stock closes at 510p (up). OBV = 20,000 + 15,000 = 35,000.
Day 3: stock closes at 505p (down). OBV = 35,000 - 12,000 = 23,000.
Day 4: stock closes at 505p (unchanged). OBV = 23,000.
The absolute value of OBV is less important than its direction and whether it diverges from price. Because the starting point is arbitrary (you choose when to begin the cumulative calculation), the number itself has no meaning in isolation. What matters is whether OBV is rising, falling or diverging from the underlying price movement.
OBV trading strategies
1. OBV trend confirmation
The most fundamental use of OBV is confirming the direction of a price trend. In a healthy uptrend, OBV should be rising alongside price, reflecting that higher prices are being accompanied by increasing buyer volume. In a healthy downtrend, OBV should be falling alongside price. When price and OBV move together, the current trend has conviction behind it and is more likely to continue. This approach is applicable across shares, indices and commodities markets.
2. OBV divergence
Divergence is the most powerful OBV signal. It occurs when price and OBV move in opposite directions:
Bullish divergence: price makes a lower low, but OBV makes a higher low. This suggests that selling pressure is weakening despite price falling, which may precede an upward reversal. For example, if a FTSE 100 stock falls to a new low on declining volume, OBV may not confirm the low, warning that bears are losing conviction.
Bearish divergence: price makes a higher high, but OBV makes a lower high. This suggests that buyers are less committed to the new high than they were previously, warning that the upward trend may be losing momentum. This is one of the more reliable reversal signals OBV produces, though it should always be confirmed with additional analysis.
OBV across different markets
Market | How OBV applies | Key consideration |
Shares | OBV is most effective; volume data is comprehensive and precise | Most shares have reliable, exchange-reported daily volume data making OBV highly accurate |
Indices | Useful at index level using constituent volume; also applicable to index ETFs | Index-level volume can be less precise than individual stock volume; ETF volume adds to signal |
Commodities | Applicable to futures-based commodity markets with reported volume | Futures volume rolls across contract months; ensure you use the most active contract |
Forex |
Limitations of the OBV indicator
Not suitable for day trading: OBV is typically calculated on daily closing prices, meaning intraday traders cannot use it to identify signals within a single session. By the time the day's OBV figure is available, the trading day is already over.
False signals around corporate events: a surprise earnings announcement, dividend declaration or major corporate news can cause a sudden spike in volume that moves OBV sharply without representing a genuine change in trend direction. OBV can temporarily mislead traders in these circumstances.
Limited for low-volume assets: OBV is most reliable for liquid, high-volume markets. For thinly traded small-cap stocks or exotic forex pairs, volume data is sparse and the OBV signal loses its reliability.
Arbitrary starting point: because OBV is a running cumulative total from an arbitrary start date, different charting platforms may show different OBV values for the same security. The absolute number is meaningless; only the direction, slope and divergence from price carry analytical value.
Should not be used in isolation: OBV works best when combined with other technical analysis tools. Using it alongside support and resistance levels, moving averages and candlestick patterns produces more reliable signals than relying on OBV alone.
OBV FAQs
What is on-balance volume (OBV)?
On-balance volume (OBV) is a technical momentum indicator that tracks cumulative volume by adding volume on up-days and subtracting it on down-days. It signals whether money is flowing into or out of an asset and can be used to confirm price trends or identify divergences that may precede reversals. It was developed by Joseph Granville in 1963.
How do you read OBV?
The direction of OBV matters more than its absolute value. A rising OBV alongside rising price confirms an uptrend. A falling OBV alongside falling price confirms a downtrend. The most powerful signals occur when OBV diverges from price: OBV rising while price falls (bullish divergence) or OBV falling while price rises (bearish divergence) can warn of an impending trend reversal.
Is OBV a leading or lagging indicator?
OBV is classified as a leading indicator because it can anticipate potential price moves before they happen, based on volume behaviour. This contrasts with lagging indicators like moving averages, which confirm trends after they have already begun. However, OBV can also produce false signals, so it should be used in conjunction with other tools.
What is the best market to use OBV on?
OBV works best on individual shares and exchange-traded products where volume data is comprehensive and precise. It is applicable to indices and commodity futures, and can be used in forex markets using tick volume as a proxy, though the signal is less reliable there due to the absence of centralised exchange volume data.
