On this page
Cumulative sell volume — Tape & flow, in its own panel below the chart.
What Cumulative sell volume measures
Selling is identified by aggressor side — trades printed into the bid — summed per bar across usable levels, then accumulated within the session. The running total restarts at zero at each session open, anchored on the CME boundary of 17:00 Central Time, the same anchor the buy leg uses, so the two lines are always directly comparable. A bar with unavailable data interrupts the running total for the remainder of that session instead of being treated as zero selling. The construction mirrors cumulative buy volume exactly, deliberately, so that any difference between the two lines comes from the market and never from the method.
The formula, as implemented
This is not how the indicator is usually defined elsewhere — it is what the shipped code computes, documented next to the implementation:
Volume VENDEUR cumulé de la session — miroir exact de cum-buy-volume (Σ sellVolume, reset à chaque ouverture CME via `splitSessions`).
How to read it
- The vertical distance between the two legs at any moment is the session's cumulative delta, while their individual steepness shows what produced it.
- A sell line climbing steeply while price holds is the situation to inspect bar by bar: selling is being met by something.
- When both lines accelerate together, participation rose without a directional winner — the context in which net-flow readings say least.
- Slope changes are the events worth marking; the absolute height only tells you how much has traded so far today.
- Treat any interruption of the line as missing data for the rest of the session, never as an absence of selling.
Parameters and defaults
Colour and smoothing length are the only inputs, since the session anchor belongs to the definition. Smoothing stays at 1 and leaves the raw cumulative in place. If you do smooth this leg, apply the same value to the buy leg, otherwise the visual comparison between the two becomes an artefact of unequal lag.
| Parameter | Type | Default | Range |
|---|---|---|---|
| Smoothing | number | 1 | 1 – 200 |
What it does not show
The series counts only aggressive selling, so limit sell orders that are lifted by buyers land on the buy side; the line is not a measure of selling interest in general. It carries no price information and no positioning information. Values cannot be carried across the session reset, a data gap voids the remainder of the session, and on instruments that do not follow the anchored session the reset lands at an arbitrary moment in their activity.
Related indicators
- Tape Speed — Tape & flow
- Diagonal Imbalances — Tape & flow
- Stacked Imbalances — Tape & flow
- Absorption Score — Tape & flow
- Unfinished Auctions — Tape & flow
- Effort vs Result — Tape & flow
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Frequently asked questions
- What does rising cumulative sell volume with flat price suggest?
- That aggressive selling kept arriving without moving price down, which describes selling being met by resting bids. It is a description of what traded, not evidence of a reversal; the level involved should be checked on the footprint, and the following bars decide whether it held.
- Does cumulative sell volume include limit sell orders?
- No. Classification follows the aggressor, so a resting sell order that a buyer lifts counts as buying. Only trades initiated into the bid add to this line, which is why it measures selling pressure rather than selling interest.
- How should cumulative buy and sell volume be compared?
- Plot them in the same pane and watch the two slopes rather than the two heights. Both legs reset together at the session open, so any comparison you make is valid inside a session and meaningless across one.