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 Optimer Pharmaceuticals (Nasdaq: OPTR), which develops advanced hospital products such as highly specialized antibiotics, fell as much as 15.7% today on very heavy trading.

So what: Optimer just reported fantastic sales in the third quarter but still saw a disappointingly large net loss. Impatient investors appear disillusioned by the prognosis that bacterial-diarrhea treatment Dificid won't break even for about three years.

Now what: The market drop notwithstanding, two analyst firms reupped their respective buy ratings on Optimer today with price targets between $19 and $20 per share. Clostridium difficile-related diarrhea doesn't present a huge market like prostate cancer does for Dendreon (Nasdaq: DNDN) or multiple sclerosis for Elan (NYSE: ELN), but it's certainly large enough to sustain a small-cap like Optimer. The company also chose to introduce Dificid in Canada yesterday, perhaps in a failed attempt to distract investors from disappointing earnings with the promise of international growth. Canada is the first non-U.S. market to start a Dificid trial program, and it's a big world out there.

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