Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of private post-secondary school Education Management (Nasdaq: EDMC) are heading into graduation season on wobbly legs, posting a brief 5% gain followed by an equally quick 10.1% drop. In the end, the stock settled around 2% above last night's closing price, all on feeble trading volume.

So what: There isn't much going on in paid-education land today. Rival ITT Educational Services (NYSE: ESI) saw a similar low-volume decline, though without the severe spike-and-drop swings of Education Management.

Now what: ITT's much higher average trading volume probably saved that stock from Education Management's flailing today. Low-volume stocks are easily manipulated, whether intentionally or not, and an even lower-volume trading day just magnifies the liquidity problem. This is why we Fools always prefer set-price limit orders over more random market orders on that class of investments.

Interested in more info on Education Management? Add it to your watchlist.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.