Up/down Volume

What is Up/down Volume?

Up/down volume is a breadth measure that splits a session's total exchange volume by direction: up volume is the combined volume of advancing issues, down volume the combined volume of decliners, summed across a universe such as the NYSE or Nasdaq. The difference between the two (the VOLD spread on many platforms) shows where the volume actually went, which issue counts alone cannot: two thousand advancers on thin volume is a weaker statement than fifteen hundred advancers carrying the day's heaviest turnover. A running total of the daily net figure is the Cumulative Volume Index, the volume-weighted cousin of the advance/decline line covered under advance/decline internals.

Extreme one-sided days matter most. Sessions where up volume overwhelms down volume by roughly nine to one, a threshold Martin Zweig studied, feed several breadth-thrust rules, while equally lopsided down-volume days mark liquidation pressure.

The measure has a well-documented research trail. Zweig published his nine-to-one findings in Winning on Wall Street in 1986. Paul Desmond of Lowry Research pushed the logic further in work that won the 2002 Charles Dow Award, defining 90% downside days as panic liquidation and finding that durable bottoms were historically confirmed by a 90% upside day soon after. Richard Arms had already folded the same inputs into his 1967 Arms Index, dividing the advancer-decliner ratio by the up-down volume ratio.

Reading the series well means knowing what feeds it. Up and down volume are exchange-level aggregates, published per venue for the NYSE and Nasdaq and streamed intraday as running totals, commonly under UVOL and DVOL tickers with the net spread quoted as VOLD. Composition matters: the NYSE tape includes closed-end funds, preferreds, and other non-common issues, so some analysts track common-stock-only versions. Because every share of volume counts equally, the series measures participation rather than market capitalization, so it can disagree with a cap-weighted index.

How to Read Up/down Volume on a Chart

There is no pattern on the price chart; identification means loading the right series and classifying the session.

1. 1Chart the exchange's up-volume and down-volume series or their difference, typically via UVOL, DVOL, and VOLD symbols; lacking a spread symbol, a ratio chart of the two works.
2. 2Classify trend days early: a spread that opens skewed and widens all session, one side running several times the other, supports trend-day tactics, especially when the TICK Index agrees.
3. 3Classify balance: a spread oscillating around zero or flipping sign repeatedly marks two-way rotation, with little directional edge from breadth.
4. 4For thrust or washout study, compute the closing up share, up volume divided by up plus down volume; 90% or more marks a genuinely one-sided session.

How it's calculated

Exchange-level breadth that splits a session's total volume into the part traded in advancing issues versus the part traded in declining issues.

Volume in unchanged issues is excluded, and universe composition matters: the NYSE tape includes funds and preferreds, so some analysts track common-stock-only versions.

Because the CVI's base is arbitrary, read its slope and divergences against the index rather than its absolute level.

The 90 percent thresholds follow Martin Zweig's 9-to-1 up-volume day studies and Lowry Research's 90 percent downside-day work.

How traders use it

• As an intraday conviction gauge: day traders watch the running up/down volume spread alongside the TICK; a spread that grinds steadily in one direction supports trend-day tactics, while a spread oscillating around zero argues for range tactics.
• As confirmation for index moves: a new high backed by strong net up volume is better supported than one where up volume barely exceeds down volume, and a persistent divergence between price and cumulative volume breadth is a classic warning, though it can run for a long time before it matters.
• As a thrust and washout detector: runs of nine-to-one up-volume days after a decline are read as initiation evidence, and nine-to-one down days as capitulation candidates, with the caveat that a single extreme day reverses nothing by itself.
• As an input to composite gauges: the Arms Index pairs it with issue counts for a short-horizon extremes read, and smoothed net-volume tools such as the library's Swenlin Trading Oscillator turn the daily spread into a swing-timing series.
• As a participation check: comparing volume breadth with the % of stocks above key moving averages separates broad advances from narrow megacap-driven ones, while a VIX backdrop helps grade lopsided down days as panic or drift.

Up/down Volume vs Other Breadth Gauges