Turnover rate: volume relative to what exists

Companion to the volume ratio post. A second normalization, and one I rarely see used here: volume divided by shares actually available to trade. Ten million shares traded means one thing on a company with a hundred million tradeable shares and something entirely different on one with twelve million. The first is a normal day. The second is the entire float changing hands, which is a different event with different consequences. What it gives you that dollar volume doesn't: dollar volume tells you whether *you* can get filled. Turnover tells you how much of the ownership actually moved, which is closer to what you mean when you say a name is "in play." It's also a cleaner way to compare a small cap to a large cap. Both can have the same dollar volume; only one of them has just turned over a fifth of itself. Worth computing even if you never trade on it directly, because it changes which names look interesting.