Trading Volume: What It Counts, How to Read It With Relative Volume, and Real S&P 500 and Bitcoin Data

Trading volume is the quantity of an asset that changed hands during a period: shares for a stock or an ETF, contracts for futures and options, units of the coin for a cryptocurrency. TradingView describes the Volume indicator as a measure of how much of an asset has traded in a given period, and every volume indicator on this site starts from it. A volume bar says how active the market was, not which side won: each share traded has one buyer and one seller.

How volume is counted and read

On a stock exchange, volume is the number of shares traded. On a crypto chart, it is usually the volume of the venue that supplies the chart, not the whole market: Bitcoin trades on many exchanges at once. Raw volume also drifts over the years, so a reading only means something next to the asset’s recent history, which is what relative volume measures.

StockCharts uses a 50-period simple moving average by default. It reads an RVOL above 1 as above-average volume, warns that 1.1 may not be worth acting on, writes that many day traders look for an RVOL over 2.0, and considers anything over 4.0 a volume spike rather than a typical reading. It adds that a spike of 4.0 or more, especially when the price is overbought or oversold, can foreshadow a reversal.

TradingView lists the usual readings of volume with price: a rise on rising volume as a confirmed trend, a rise on falling volume as a possible lack of interest, a sharp move with a surge in volume as a possible exhaustion, and a breakout on rising volume as stronger than one on flat or falling volume.

Trading volume on a real chart

The chart shows the daily volume of the S&P 500 ETF, in millions of shares, with the average of the previous 50 sessions, from February 7 to July 31, 2025, with dividend-adjusted prices. Volume ranged from 26.0 million shares on February 10, an RVOL of 0.54, to 256.6 million on April 7, when the ETF closed at 496.15 after a 0.18% loss. Against the 62.7 million shares of the previous 50 sessions, that day’s RVOL was 4.09, the only reading of the window above StockCharts’ 4.0 spike threshold. Had the average included the day itself, the reading would have been 3.82. RVOL reached 2 or more on seven days: March 4, and April 3, 4, 7, 8, 9 and 10, a cluster that began with closes down 4.93% on April 3 and 5.85% on April 4. The ETF made its low close of the window, 488.38, the next day, April 8, rose 10.50% on April 9 on 241.9 million shares, fell 4.38% on April 10, and ended the window on July 31 at 623.60, 25.7% above the April 7 close. This is the case StockCharts describes, a spike of 4.0 or more near an oversold low; one case is not a rate of success.

The spike also moved the average. The average of the previous 50 sessions rose from 48.2 million shares at the start of the window to 85.0 million on May 5, so ordinary days that followed looked quiet by comparison: on May 9, 37.6 million shares gave an RVOL of 0.44, the lowest of the window. By July 31, the average was back to 70.9 million.

When volume trades: Bitcoin by day and hour

Volume also follows the calendar. On Bitcoin, which trades every day, the median weekend day of the year from October 29, 2025 to October 28, 2026 traded 0.48 times the volume of the median weekday (Saturday 0.45, Sunday 0.51; the five weekdays all between 0.97 and 1.04). The dips in the chart above are those weekends. By hour, the four hours from 13:00 to 17:00 UTC carried 26.6% of the year’s volume, against 16.7% for an even spread; the busiest hour, 14:00 UTC, carried 7.41%, and the quietest, 21:00 UTC, 2.89%. Bitcoin volume here comes from a single exchange, not from the whole market. A volume average that mixes weekdays and weekends, or an RVOL measured on a quiet hour, inherits these rhythms.

Does volume confirm breakouts?

Our bench tests chart patterns detected by rule against random entries (see our methodology). For volume on its own, we measured simple breakouts: the first close above the highest close of the previous 20 days, without costs, and the change over the next 20 days.

On the ETF, from 1993 to 2026, the 839 breakouts followed by 20 days of data (the latest one is too recent to count) came on lighter volume than usual: their median RVOL was 0.85 on the 837 with 50 previous sessions to average, against 0.93 for all days, and only 43 had an RVOL of 1.5 or more. Those 43 did better than the low-volume ones, but 43 cases is a small sample. On Bitcoin, from August 17, 2017 to October 28, 2026, 232 breakouts had 20 days of data after them, with a median RVOL of 1.09; the result was mixed: a higher mean, a slightly lower share of rises. RVOL here divides by the average of the previous 50 days, as StockCharts does. These are descriptive averages, not a trading test.

Volume is the raw material of the volume indicators: the Volume Oscillator compares two of its averages, On Balance Volume signs it by the direction of the close, and the volume profile spreads it by price level.