# Cumulative delta > The running sum of buyer-aggressed minus seller-aggressed volume — one line tracking which side has been crossing the spread harder, accumulated trade by trade. - Canonical: https://hadalinstruments.com/glossary/cumulative-delta/ - Term set: https://hadalinstruments.com/glossary/ --- Volume answers how much; delta asks the sharper question — how much, and who insisted. The construction inherits everything from the [footprint chart](/glossary/footprint-chart/)'s machinery: classify each print by aggressor — at the ask, a buyer paid to cross; at the bid, a seller did; prints between the quotes take a stated rule — then sum sizes with sign. Rendered per bar it gives delta and its range; accumulated it gives the cumulative line this entry names. The classification is a convention, not a revelation, and every delta figure quietly carries its convention the way a profile carries its window: change the rule and identical prints draw a different line. What the line uniquely shows is the gap between aggression and progress. Price and delta advancing together is the unremarkable case. The interesting prints are the disagreements — price pushing to new extremes while delta stalls, or delta pressing hard while price refuses to move. The vocabulary calls the first **divergence** and reads it as absorption: aggressive flow being met by resting size that declines to budge, the tape's-eye view of the [absorb/sweep](/glossary/absorb-sweep/) balance the book measures directly. The reading is coherent and it is an inference — delta is built from the tape, and absorption is a claim about the book, so the line is always reasoning about a layer it cannot see. Its book-side sibling, [order flow imbalance](/glossary/order-flow-imbalance/), watches that layer directly, which is why the two instruments disagree productively. The FX caveat is structural, not a footnote. Delta was born where a consolidated tape makes "the market's trades" a real object. Spot FX has no such tape, and much of it quotes without dependable per-trade sizes — so an FX delta is the signed sum of **one feed's** business under one convention: a genuine measurement of that book, and a different line on a different feed. Quoting an FX delta without its feed is quoting a temperature without saying which room. The divergence readings, like every reading in this family, are testable — outcomes after divergences against matched non-divergent extremes, per convention, per feed — and the [two lenses](/glossary/the-two-lenses/) keep the line's arithmetic separate from the story told over it. ## Commonly confused with Neighbouring concepts that get used interchangeably, and the distinction that actually separates them. - **Volume** — Volume counts everything that traded; delta signs it first. A heavy-volume bar with delta near zero and the same bar with delta deeply one-sided are different events wearing the same volume print — the signing is the information. - **[Order flow imbalance](https://hadalinstruments.com/glossary/order-flow-imbalance/)** — Order flow imbalance is built from the book — arrivals, cancellations and replenishment of resting orders; delta is built from the tape — executed trades signed by aggressor. Related instruments pointed at different layers: one watches intention change, the other counts consummated aggression. - **[A footprint chart](https://hadalinstruments.com/glossary/footprint-chart/)** — The footprint keeps the per-bar, per-price ledger; delta sums that ledger into one running number. The compression is the point and the cost: delta answers "who has been more aggressive" while discarding where, at what prices, against what resting size. - **Sentiment** — Delta measures executed aggression, not opinion. A market can lean bullish in every survey while delta runs negative for hours, because delta only counts those who paid the spread to act — and only on the feed being measured. ## How to measure it in your own data A definition you cannot test is a definition you have to take on trust. This is the shortest honest route from the concept to a number you computed yourself. - **Records you need** — Per-trade prices and sizes with the bid/ask context to classify each print's aggressor — and the feed's identity, since in FX the tape being summed is one book's slice of the market. - **What you compute** — Classify each trade by the stated convention — at the ask, buyer-aggressed; at the bid, seller-aggressed; a stated rule for prints between — then accumulate signed size. Per-bar delta, its high-low range, and the running cumulative line are the standard renderings; the convention is a parameter carried by all three. - **What the answer tells you** — Price and delta agreeing reads as initiative; price advancing while delta stalls or drains — the divergence reading — is taken as absorption, aggression being met by resting size that does not move. The picture is checkable; the interpretation is an inference about the book made from the tape. ## Questions and answers ### What is cumulative delta in trading? A running total of signed volume: each trade classified as buyer- or seller-aggressed by where it printed against the quotes, sizes summed with sign. The line answers one question — which side has been crossing the spread harder, cumulatively — on the feed being measured. ### What is a delta divergence? Price making a new extreme while cumulative delta declines to confirm it — new highs on fading buyer aggression, or new lows on fading seller aggression. The standard reading is absorption; the honest addition is that the reading is an inference, and its hit rate is a measurable proposition rather than a given. ### Is cumulative delta accurate in forex? It is exactly as accurate as its inputs: an aggressor classification that is a convention, applied to a tape that in spot FX is one feed's partial record, often without dependable per-trade sizes. The line is a real measurement of that feed. Treating it as the market's delta imports a consolidated tape FX does not have. ### Why did delta stay positive while price fell? Because aggression and progress are different quantities: buyers can keep crossing the spread into resting supply large enough to absorb them, and price grinds lower anyway. That disagreement is not the indicator failing — it is the one thing delta uniquely shows, whatever it turns out to predict. ## Related terms Derived from the links this entry makes and the entries that link back to it. - [Absorb/Sweep](https://hadalinstruments.com/glossary/absorb-sweep/) A microstructural market dynamic where limit orders (absorption) interact with aggressive market orders (sweeping) across multiple price levels, defining liquidity transition phases. - [Delta divergence](https://hadalinstruments.com/glossary/delta-divergence/) Price printing a new extreme that cumulative delta declines to confirm — fresh highs on fading buyer aggression, or fresh lows on fading seller aggression — read as absorption at the extreme. - [Footprint chart](https://hadalinstruments.com/glossary/footprint-chart/) A candle opened up: per price level within each bar, the volume that traded — usually split by aggressor side — so the bar shows not just where price went but who paid to move it. - [Order flow](https://hadalinstruments.com/glossary/order-flow/) The stream of orders arriving at a market — aggressive orders consuming resting size and passive orders posting it — and, by extension, the discipline of reading that stream from book and tape data. - [Order Flow Imbalance (OFI)](https://hadalinstruments.com/glossary/order-flow-imbalance/) A measure of net buying pressure constructed from changes at the top of the order book — additions, cancellations and executions on each side, netted over an interval. - [The Two Lenses](https://hadalinstruments.com/glossary/the-two-lenses/) A framework in quantitative trading where every metric is evaluated through both its theoretical statistical properties and its physical microstructure execution constraints. ## Cite This Definition APA BibTeX HTML Hadal Instruments. (2026). Cumulative delta. Hadal Glossary. https://hadalinstruments.com/glossary/cumulative-delta/ Version 6b39ebf, 2026-08-30. @misc{hadal_2026_cumulative-delta, author = {Hadal Instruments}, title = {Cumulative delta}, year = {2026}, url = {https://hadalinstruments.com/glossary/cumulative-delta/}, howpublished = {Hadal Glossary}, version = {6b39ebf}, note = {Pre-launch publication; version dated 2026-08-30} } Source: Hadal Instruments, Cumulative delta. Original Research Copy Citation **Version 6b39ebf** identifies the commit that last changed this page in Hadal's content repository. That repository is not public, so the identifier does not resolve externally — it is published so a citation pins one specific state rather than a moving page. To obtain the exact version cited, use the [press and research route](https://hadalinstruments.com/press/).