Its divergence from price is the best-known early warning: price rises while OBV falls = a rally without participation.
The short answer
- What is On-Balance Volume (OBV)?
- On-Balance Volume: volume is added on up candles and subtracted on down candles, cumulatively.
- When does OBV get it wrong?
- Its absolute value means nothing. Only the direction matters. See its current reading on platform symbols, at the latest daily close, in the "Reading now" table on this page. See its current reading →
Reading now
| Ticker | Value | Five sessions ago | Status |
|---|---|---|---|
| SPY | 374.56M | 467.39M | Lower than five sessions ago |
| QQQ | 578.57M | 686.24M | Lower than five sessions ago |
| IWM | 571.16M | 657.42M | Lower than five sessions ago |
| DIA | 171.64M | 169.72M | Higher than five sessions ago |
A description of where the number sits against its thresholds. It is not an entry or exit signal.
Indicator limit
Its absolute value means nothing. Only the direction matters.
Read it with
Relative Strength Index: a divergence that shows up with a divergence in RSI at the same time is a stronger warning than either alone.
Answers: does volume back it?
What it actually does
On-Balance Volume builds a simple cumulative line: the session's full volume is added if price closes up and subtracted if it closes down. The absolute number means nothing, and all the meaning is in the direction of the line. Is volume piling up in up sessions or down sessions?
How it is read in practice
The idea is that volume sometimes leads price. Quiet institutional accumulation lifts the line before price jumps, and distribution pulls it down while price stalls. When the line and price point the same way, that confirms the move. When they differ, it is a warning.
The difference is the point of the tool
Price makes a higher high while the volume line makes a lower high. That means the last leg up came with less participation, a thin-based rally. The reverse holds at lows: price falls to a new low while the line refuses to fall, which hints that selling is exhausted.
Hypothetical example
A stock sits in a narrow range for three weeks while the volume line climbs steadily. Someone is accumulating without lifting the price. The breakout that follows finds a base, and the person reading the line saw it being built.
Where it errs and why
It treats every session equally: a close one cent above yesterday adds the full volume, just like a close up 5%. It is also distorted on mechanical event days (contract expiry, index rebalances), when volume swells without any opinion behind it.
Read it with
Read it with the Money Flow Index, which weights by volume and price together and so smooths out some of its flaws. Add relative volume (RVOL · Relative Volume), which tells you whether today's volume is unusual at all, and off-exchange trading data, which shows accumulation the visible order book does not. All three answer one question: does money follow price or leave it?
Where to see it on the platform
The symbol card shows the share of off-exchange (dark pool) trading in its weekly volume, and the market scanners rank by relative volume, so anomalies show up before they appear in price.
