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 zinc producer Horsehead Holding (Nasdaq: ZINC) dropped as much as 12.6% overnight on about twice the average trading volume, reminding shareholders of Marlon Brando discussing offers you can't refuse.

So what: The big news on Horsehead today is a fresh debt offering. The company aims to raise between $80 million and $100 million in convertible (read: dilutive) notes to finance the construction of a new zinc-mining facility. Investors seem to be focusing more on the dilutive effects of the offering than on the potential business growth therein.

Now what: This is not the first time Horsehead shares moved in the opposite direction of what looks like good news. The crash makes some sense; one of this five-star CAPS stock's main attractions was its squeaky-clean balance sheet, which won't be the case anymore. Still, this longtime Motley Fool Hidden Gems recommendation has treated investors very well over the last year, with a 47% gain even after this recent drop, beating peer US Ecology (Nasdaq: ECOL) and running close to much larger rival Teck Resources (NYSE: TCK). I see an opportunity here as Horsehead aims to capitalize on a hot market for commodity metals. Now the shares are on sale, too.

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