Cumulative Delta

Cumulative delta is the running total of buy volume minus sell volume over a session or defined period. It shows whether aggressive buyers or sellers have been dominant and is one of the most widely used order flow indicators in futures trading.

Cumulative delta is the sum of all buy-initiated volume minus all sell-initiated volume from the start of a session (or any defined period) to the current bar. It tracks the net aggression of market participants: positive values mean buyers have been more aggressive, negative values mean sellers have been more aggressive.

Cumulative Delta = Σ (Ask Volume − Bid Volume)

Volume executed at the ask price is classified as buy aggression. Volume executed at the bid price is classified as sell aggression.

How to read cumulative delta

Rising price + rising cumulative delta: buyers in control, trend has conviction. Normal, healthy uptrend.

Rising price + falling cumulative delta: price rising despite net sell aggression. Sellers are absorbing the move. This divergence often precedes a reversal.

Falling price + falling cumulative delta: sellers in control, trend has conviction. Normal downtrend.

Falling price + rising cumulative delta: price falling despite net buy aggression. Buyers are being absorbed. Often precedes a reversal to the upside.

Delta divergence

The most actionable signal from cumulative delta is divergence from price. When price makes a new high but cumulative delta fails to confirm (or is declining), it suggests the move is being sold into: not supported by genuine buying pressure.

This divergence does not guarantee a reversal, but it shifts the probability and is a key filter for trade entry and exit decisions.

Session reset

Cumulative delta typically resets at the start of each session or each day. Some traders use a rolling cumulative delta that spans multiple sessions or a custom lookback period. The reset point significantly affects interpretation: compare delta within the same context window.