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 industrial parts manufacturer Sun Hydraulics (Nasdaq: SNHY) lost pressure today, falling as much as 11.7% on what counts as heavy volume for this thinly traded stock.

So what: It was a bad day for heavy manufacturing stocks in general: Sun rival Flowserve (NYSE: FLS) fell 6% while sector neighbors Terex (NYSE: TEX) and Manitowoc (NYSE: MTW) fared even worse. For the record, neither Sun nor any of its known major customers shared any significant news today.

Now what: Sun Hydraulics now trades for just 57% of the 52-week highs that were set after a happy earnings report in May. Much of those gains were wiped out by third-quarter guidance that was as gloomy as the second quarter's was bright. We're looking at a micro-cap stock whose management team doesn't seem to have a handle on market trends -- resulting in a highly volatile stock. Despite a perfect five-star CAPS score, a long history on our Motley Fool Hidden Gems scorecard, and a pleasantly boring business model, Sun doesn't send out rays of sunny, safe investing even at these low prices.

Interested in more information about Sun Hydraulics? Add it to My Watchlist.