Core terms
Float rotation
The day's volume divided by the float. Thirty million shares traded on a ten-million-share float is three "rotations."
Traders use float rotation as a rough measure of how heavily a small-float stock is being traded relative to its size. It is simple arithmetic on two numbers, and both have problems. Volume counts every share each time it trades, so the same shares can be bought and sold many times; one rotation does not mean every holder sold. The float in the denominator is an estimate and may predate recent share issuance.
Example (Illustrative): a stock with a 5 million-share float that trades 40 million shares has "rotated its float" eight times. If 10 million new shares were issued last week and the float was not updated, the true ratio is closer to 2.7.
What traders should verify
Use rotation alongside dollar volume and the float's as-of date, not as a signal by itself.
Do not conflate
Trader usage; no official definition. A high ratio says trading was heavy relative to the estimated float, not who traded or why.
Primary source
Trader usage: there is no official definition, and platforms and tools may calculate it differently.