Relative volume (RVOL)
Relative volume, or RVOL, compares how much a stock has traded today with how much it usually trades. An RVOL of 2 means twice its normal volume, and momentum traders use it to tell a stock that is in play from one that is just drifting.
Why it matters to a small-cap momentum trader
Volume is attention, and a big move without it rarely lasts. A small cap trading many times its usual volume has new buyers and sellers in it, usually because of news, and that is where the liquidity and the range are. RVOL also puts stocks on the same scale: a stock that trades a few hundred thousand shares a day and one that trades tens of millions can both be measured against their own normal.
How it is measured
Full day. Today's volume divided by the stock's average daily volume over a recent period.
Time of day. Today's volume so far divided by what the stock usually trades by the same time of day, so 10:00 a.m. is compared with 10:00 a.m. This is the better intraday measure.
Before the open. Almost nothing usually trades at 7:00 a.m., so the time-of-day number can swing wildly in the pre-market, and pre-market scanners often compare with the average full day instead.
There is no standard definition, so two scanners can show different RVOL for the same stock.
Relative volume in Hindsight Markets
The scanner has relative volume by time of day, for the full day, and over the last few minutes, each counted only from what had traded by that moment in the replay.
Practice this on a real past day in Hindsight Markets
Replay a real morning, sort the scanner by relative volume, and see which stocks the volume found first.