On Balance Volume, Explained

On Balance Volume (OBV) is a momentum indicator that turns volume into a single running line to show whether volume is flowing into or out of an asset. It was popularized by Joseph Granville in the 1960s. The rule is simple: on a day when price closes higher, that day's volume is added to a running total; when price closes lower, the volume is subtracted. Traders watch the direction of the resulting line, not its raw value, to judge whether buying or selling pressure is behind a move.

What OBV measures

The idea behind OBV is that volume often moves before price. If large players are accumulating, volume flows in on up days even if price has not broken out yet, and the OBV line climbs. If they are distributing, volume drains out on down days and the line falls. By keeping a running tally, OBV compresses that flow into one easy-to-read trend.

The single most important thing to understand is that the actual number OBV shows is meaningless on its own. It depends entirely on the arbitrary point where the calculation started. What matters is the slope and direction of the line over time, and whether its highs and lows agree with price.

How OBV is calculated

The math is deliberately simple, which is part of its appeal. For each period:

• If today's close is above yesterday's close, add today's volume to the running total.
• If today's close is below yesterday's close, subtract today's volume.
• If the close is unchanged, the total stays the same.

Notice that OBV treats a small up-close and a large up-close identically: the full day's volume is added in both cases. It cares only about the direction of the close, not how far price moved. That simplicity makes OBV easy to read but also blunt, and it is one reason the tool works better as confirmation than as a precise trigger.

Reading the OBV line

There are three main things traders look for in OBV:

• Trend confirmation. When price makes higher highs and OBV also makes higher highs, volume is supporting the advance. A rising price with a rising OBV is a healthier trend than a rising price on a flat OBV.
• Divergence. When price makes a new high but OBV fails to, the move may be running on thin volume and losing conviction. The bullish mirror is price making a lower low while OBV holds a higher low.
• Breakout support. An OBV line breaking to new highs ahead of price can hint that accumulation is underway before a visible breakout.

Tip: OBV divergence is a warning, not a trigger. Volume can diverge from price for a long time before anything happens. Wait for price itself to confirm before acting.

How to use OBV

OBV is a confirmation layer that works best on top of clear price structure, not a standalone buy or sell button. A disciplined approach:

• Read price first. Establish the trend and key levels using price and structure, then use OBV to confirm or question them.
• Compare the slopes. Ask whether OBV is confirming the price trend or quietly diverging from it.
• Draw trendlines on OBV. A break of an OBV trendline can precede a break in price, giving an early heads-up worth watching.
• Pair with a momentum tool. OBV describes volume flow; a tool like the RSI indicator describes momentum. Together they give a fuller picture than either alone.
• Act on candle close. OBV updates as the bar builds, so only the closed-bar value is stable.

Because volume divergences and confirmations are easy to miss across many charts, hunting them by hand is slow and inconsistent. A scanner like TraderIndicator can watch crypto, stocks, and forex on TradingView and surface only the setups that meet a defined ruleset, each with an entry, stop, and reason attached, and it locks signals on candle close so they do not repaint. It handles the searching; you keep the judgment about whether a setup fits your plan.

OBV vs other volume tools

OBV is the simplest of the volume family, which is both its strength and its weakness. Because it adds the full day's volume regardless of how large the price move was, it can overstate the importance of a small up-close on heavy volume. Tools such as VWAP and volume profile use volume differently: VWAP weights price by volume to find an average trading level, while volume profile shows where volume traded across price rather than over time. None of these replace each other. OBV answers whether flow is trending up or down; the others answer where value sits and where activity concentrated.

Common OBV mistakes

• Reading the number. The raw OBV value is arbitrary. Only its direction and its highs and lows relative to price mean anything.
• Trading divergence blindly. Divergence can persist far longer than expected. It is a reason to watch closely, not to enter immediately.
• Ignoring the close-direction quirk. Because OBV adds the whole day's volume for any up-close, a marginal close can add heavy volume that overstates buying strength.
• Using it alone. OBV describes only volume flow. Combine it with price structure and a momentum tool for context.

Used as confirmation alongside price, OBV is a clean way to check whether volume backs a move. Used as a standalone signal, its bluntness will mislead you.

This article is educational and is not financial advice. Indicators describe price behavior; they do not predict the future or guarantee results. Do your own research and manage risk.