Reading Volume: What It Tells You and What It Doesn't
Volume is the most available secondary data most traders have and among the most misinterpreted. It confirms; it does not predict.
Volume measures how much changed hands. That is genuinely useful information, provided you are clear that it describes conviction rather than direction.
Confirmation
A price move on heavy volume reflects broad participation. A move on thin volume may be a handful of orders in a quiet market. The same 2% rise means different things depending on how many participants were involved.
This makes volume most valuable as a filter on other signals rather than a signal itself.
Spikes
Unusual volume — several times the recent average — almost always means information arrived or a large participant acted. It marks a moment worth examining. It does not tell you which way things resolve; the largest volume days occur at both tops and bottoms.
Divergence
When price makes a new high but volume is materially lower than at the previous high, fewer participants are supporting the move. This is a caution flag, not a reversal signal. Trends can continue on declining volume for a long time.
Volume divergence tells you a move is less well supported. It does not tell you when the support fails.
The context problem
Raw volume is nearly useless for comparison. Volume varies by asset, by day of week, by session, and around holidays and index rebalancing. What matters is volume relative to its own recent average for that instrument, which is why a ratio is more informative than a number.
Where volume data is unreliable
- Spot forex has no central exchange, so reported volume is broker-specific and only a sample of the market.
- Crypto volume varies enormously in quality between venues, and wash trading has historically inflated figures on some.
- Equities have the most reliable data, though a meaningful share trades off-exchange and appears only with delay.
Practical use
Treat volume as a confidence weighting on whatever else you are looking at. A breakout on strong volume deserves more attention than the identical breakout on weak volume. That is a modest claim, and it is roughly the extent of what volume reliably supports.
Educational content only. Not financial advice.
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