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On-Balance Volume: Does Volume Precede Price?
On-Balance Volume is a running total of volume that adds each day's volume when price closes up and subtracts it when price closes down. It tries to show whether volume is flowing into or out of a security before that flow fully shows up in price.
Key Takeaways
- OBV adds the full day's volume on up closes and subtracts it on down closes, building a running line that tracks buying versus selling pressure.
- Granville's core claim: OBV rising while price is flat signals quiet accumulation likely to precede an upward price move.
- The absolute OBV level is arbitrary and meaningless, only the direction, slope, and divergence from price matter.
- OBV treats all volume as either fully bullish or fully bearish, which can misclassify gap-and-fade days as strong buying.
Key Takeaways
- OBV adds the full day's volume on up closes and subtracts it on down closes, building a running line that tracks buying versus selling pressure.
- Granville's core claim: OBV rising while price is flat signals quiet accumulation likely to precede an upward price move.
- The absolute OBV level is arbitrary and meaningless, only the direction, slope, and divergence from price matter.
- OBV treats all volume as either fully bullish or fully bearish, which can misclassify gap-and-fade days as strong buying.
What It Is
OBV is a cumulative volume indicator. Each period it takes the entire day's volume and either adds it to the running total, subtracts it, or leaves it unchanged, depending on how the close compares to the previous close.
Joseph Granville popularized the indicator in his 1963 book Granville's New Key to Stock Market Profits. His central claim was that volume precedes price. If OBV is rising while price is flat, accumulation is quietly happening. If OBV is falling while price is flat, distribution is quietly happening. The price move, in Granville's view, tends to follow.
The Intuition
Raw volume on its own is ambiguous. A 50 million share day can mean heavy buying or heavy selling, and the chart does not tell you which. OBV resolves that ambiguity in the simplest way possible: it labels every day's volume as either buying pressure (close up) or selling pressure (close down) and keeps a running tally.
The result is a line that trends with the balance of pressure. You compare the shape of that line to the shape of price. When the two agree, the move looks supported by volume. When they disagree, something is off.
How It Works
The rule is a three-way switch:
If close > prior close: OBV = prior OBV + today's volume
If close < prior close: OBV = prior OBV - today's volume
If close = prior close: OBV = prior OBV
That is the entire calculation. There are no parameters, no lookback windows, no smoothing. The starting value is arbitrary, often set to zero or to the first day's volume, because only the shape of the line matters.
Analysts read OBV in two main ways. The first is trend agreement: if price is making higher highs and OBV is also making higher highs, the uptrend has volume behind it. The second is divergence: if price makes a new high but OBV fails to, buying interest is thinning out even though the tape still looks strong. The reverse setup, price making a new low while OBV holds up, is read as selling exhaustion.
Worked Example
Suppose a stock trades for five days with these closes and volumes:
| Day | Close | Volume | Direction | OBV |
|---|---|---|---|---|
| 1 | 100 | 1,000,000 | start | 0 |
| 2 | 102 | 1,500,000 | up | +1,500,000 |
| 3 | 101 | 800,000 | down | +700,000 |
| 4 | 101 | 600,000 | flat | +700,000 |
| 5 | 104 | 2,000,000 | up | +2,700,000 |
Over five days the stock rose 4 percent and OBV climbed to +2.7 million shares. Up-day volume dominated down-day volume by a wide margin, which is the kind of pattern Granville associated with genuine accumulation. If price had made the same move but Day 2 and Day 5 had volumes of 400,000 while Day 3 had 2,000,000, OBV would be deeply negative and the same price rally would look suspect.
Common Mistakes
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Treating the OBV level as meaningful. The absolute value of OBV is arbitrary because the starting point is arbitrary. Two charts of the same stock on different platforms can show wildly different OBV values. Only the direction, slope, and relationship to price matter.
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Expecting OBV to track price tick for tick. OBV can drift away from price for weeks or months, especially in low-volatility ranges where small closes decide which direction the full day's volume gets stamped. Short stretches of divergence are normal noise, not signals.
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Confusing a line cross with a price signal. OBV crossing a moving average of itself, or crossing a trendline drawn on the OBV pane, is an OBV event, not a price event. Price may follow, lag, or ignore it entirely. Pair any OBV cross with price action or another indicator before acting.
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Ignoring that one flat close neutralizes a huge volume day. Because OBV treats flat closes as zero, a 100 million share session that closes unchanged contributes nothing. In thinly traded or news-driven names this can mask real accumulation or distribution.
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Using OBV on illiquid stocks. OBV assumes volume reflects broad participation. In low-float or lightly traded securities, a handful of prints can dominate the tally and produce a line that looks informative but reflects one or two players.
Frequently Asked Questions
Q: What is on-balance volume in simple terms? OBV is a running total that adds the full day's trading volume when price closes up and subtracts it when price closes down. The resulting line trends up when buyers are dominant and down when sellers are, giving a visual companion to the price chart.
Q: How does on-balance volume affect investment decisions? It helps confirm whether a price move has volume support. A rising price accompanied by rising OBV suggests genuine buying interest. A rising price with flat or falling OBV warns that the move lacks participation and may not hold.
Q: What is a real-world example of an OBV signal? A stock trades sideways for six weeks with price holding at $50, but OBV climbs steadily over that period. According to Granville's theory, institutional buyers are accumulating shares quietly. The price breakout that follows, if it occurs, has the volume evidence already built up beneath it.
Q: How can investors use OBV practically? Focus on OBV divergence from price rather than the absolute level, which is arbitrary. A simple rule: when price makes a new high but OBV fails to confirm it, reduce exposure or tighten stops, the move may be running out of volume support.
Q: How is OBV different from the Accumulation/Distribution Line? OBV applies the full day's volume based on close direction alone. The A/D Line scales each day's volume by where the close fell inside the high-low range, giving partial credit for partial closes. On gap-and-fade days they can point in opposite directions.
Sources
- StockCharts ChartSchool. "On Balance Volume (OBV)." https://chartschool.stockcharts.com/table-of-contents/technical-indicators-and-overlays/technical-indicators/on-balance-volume-obv
- Investopedia. "On-Balance Volume (OBV)." https://www.investopedia.com/terms/o/onbalancevolume.asp
- Fidelity Learning Center. "On Balance Volume." https://www.fidelity.com/learning-center/trading-investing/technical-analysis/technical-indicator-guide/obv
- Corporate Finance Institute. "On-Balance Volume Indicator (OBV)." https://corporatefinanceinstitute.com/resources/career-map/sell-side/capital-markets/on-balance-volume-indicator-obv/
Disclaimer
This article is educational content only and is not financial advice. Nothing here is a recommendation to buy, sell, or hold any security. Consult a licensed advisor before making investment decisions.