On Balance Volume Indicator
Price tells you what happened. Volume tells you whether to believe it. That’s the whole premise behind two of the oldest cumulative volume tools in technical analysis: On-Balance Volume (OBV) and the Accumulation/Distribution Line (A/D).
Both indicators run a rolling tally of volume, adding it when the evidence points to buying pressure and subtracting it when the evidence points to selling pressure. But they disagree on what counts as “evidence” — and that disagreement is exactly what makes them useful together instead of redundant.
What Is On-Balance Volume (OBV)?
OBV was developed by Joseph Granville in the 1960s, built on a simple idea: volume precedes price. If big volume is flowing into a stock, price should eventually follow — even if it hasn’t yet.
The calculation only looks at one thing: did today’s close beat yesterday’s close?
- Close higher than the prior close → add today’s full volume to the running total
- Close lower than the prior close → subtract today’s full volume from the running total
- Close unchanged → OBV stays flat
That’s it. There’s no reference to the day’s high or low, no weighting — just a binary up/down call multiplied by volume, accumulated over time.
On Balance Volume Indicator – OBV Calculation Example
Notice OBV is a running line with no fixed scale — what matters isn’t the absolute number, it’s the shape of the line relative to price.
On Balance Volume Indicator – Reading OBV: Confirmation and Divergence
OBV is used two ways:
Trend confirmation. When price makes a new high and OBV makes a new high alongside it, the move is backed by real participation. When price grinds higher on a flattening or falling OBV, the rally is running on thin volume — a classic warning sign that the move lacks conviction.
Divergence. This is where OBV earns its keep. A bearish divergence forms when price prints a higher high but OBV prints a lower high — sellers are quietly outweighing buyers even as price pushes up. A bullish divergence is the mirror image: price makes a lower low, but OBV refuses to follow, suggesting selling pressure is drying up before price shows it.
OBV divergences are early — sometimes too early. They can flag a shift weeks before price confirms it, which means they’re best used as a heads-up to tighten risk management, not a standalone entry trigger.
What Is the Accumulation/Distribution Line (A/D)?
Marc Chaikin’s Accumulation/Distribution Line asks a different question than OBV. Instead of comparing today’s close to yesterday’s close, it looks at where the close landed within today’s own high-low range.
The logic: a close near the day’s high — even on a red day — reflects buyers stepping in and defending the low. A close near the day’s low — even on a green day — reflects sellers capping the rally. A/D captures that intraday tug-of-war that OBV, with its close-to-close comparison, completely ignores.
The formula runs in three steps:
- Money Flow Multiplier = [(Close − Low) − (High − Close)] ÷ (High − Low)
- Money Flow Volume = Money Flow Multiplier × Volume for the period
- A/D Line = prior A/D value + current Money Flow Volume
The multiplier ranges from +1 (close at the exact high) to −1 (close at the exact low), with 0 meaning the close landed at the dead center of the range.
A/D Calculation Example
Compare Day 2 in this table to Day 3 in the OBV table above: a down day (100.80, lower than the prior close of 101.20) would have subtracted 25,000 from OBV. But because the close landed well above the midpoint of the day’s range, A/D still added a positive value. That’s the divergence between the two indicators showing up in real time — same data, opposite conclusion.
OBV vs. A/D: Why They Disagree
Neither indicator is “more correct” — they’re measuring different phenomena. A gap-down day that closes near its high will push A/D up while dragging OBV down. A quiet grind-up day that closes at the day’s low will do the reverse. When both indicators agree, that’s a stronger signal than either one alone; when they diverge from each other, it’s often worth digging into the price action to see which story is more representative of what’s really happening. StockCharts has a good breakdown of real chart examples where the two indicators pull in opposite directions.
Using Them Together in a Trading Plan
- Confirm the primary trend with whichever indicator fits your timeframe — OBV for swing/position views across sessions, A/D for a read on intraday accumulation.
- Watch for divergence at extremes. A stock at a multi-month high with both OBV and A/D failing to confirm is a caution flag, not necessarily a sell signal on its own.
- Cross-check against price structure. A volume divergence that lines up with a break of trendline support/resistance carries far more weight than a divergence sitting in the middle of a range.
- Don’t trade the indicator in isolation. Both OBV and A/D are best paired with price action, moving averages, or an oscillator . Treat them as a filter that adds or removes conviction from a setup you’d already be considering.
On Balance Volume Indicator – Limitations to Keep in Mind
- Cumulative indicators drift. Because every day’s volume permanently affects the running total, OBV and A/D can carry the “memory” of an old move long after it’s stopped being relevant. Watch the slope and shape, not the absolute level.
- They don’t work well on thin or erratic volume . A single large print (an index rebalance, an options expiry) can distort the line for weeks.
- A/D can be fooled by gaps. A stock that gaps up and closes at the low of a wide range can still register a negative multiplier even on an objectively bullish day. So always sanity-check the reading against the chart.
Where This Fits in the Volume Series
This is the third piece in the Volume pillar cluster. It is following tick volume in Forex and volume divergence and trend confirmation. Next up: the Money Flow Index (MFI) and Chaikin Money Flow (CMF). Two indicators that take the same accumulation/distribution logic and turn it into a bounded oscillator.
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