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: Hang on -- shares of Hanger Orthopedic Group (NYSE: HGR) fell as much as 10.7% overnight before making a modest recovery, with a huge volume spike at the bottom of the bounce.

So what: The orthopedic device wrangler and operator of orthotic and prosthetic care centers across America matched or beat revenue and earnings estimates in last night's first-quarter report and reaffirmed its existing full-year guidance. None of this was surprising in the least, but then investor expectations on this type of high-octane growth stocks often get a bit ahead of themselves.

Now what: Overheated expectations often set the stage for heartbreak, and that's what we have here: That volume spike sticking out like a sore thumb looks a lot like one large investor dumping a large batch of shares in disgust. Sporting five CAPS stars out of five, Hanger is one of the highest-rated stocks in the red-hot health-care provider field, beating such stalwarts as Quest Diagnostics (NYSE: DGX) and WellPoint (NYSE: WLP). A drop like this on a high-quality stock can be a signal to buy shares at a discount.

Interested in more info on Hanger Orthopedic Group? 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.