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 medical device developer Cerus (Nasdaq: CERS) was in need of an optimism transfusion today after shares dropped as much as 16% after the company reported fourth-quarter results.

So what: For the fourth quarter, Cerus' revenue jumped 18% from 2009 to $6.5 million, which was above $6 million that analysts were expecting. The company's per-share net loss also improved, from $0.13 last year to $0.06 this time around. The bottom line also topped analysts' estimates. Good news so far, right? Unfortunately, the company blew it when it said revenue will only grow around 20% in 2011, which would put it well short of Wall Street's expectations.

Now what: Since the company is continuing development and seeking approval for its blood-safety systems -- and, therefore, still reporting losses and cash burn -- Cerus is a speculative situation that's not suitable for all investors (and not a stock I'd put my own money into). However, for those that are taking a flyer on the stock, there's definite potential if it can bring its full vision to the commercial market. Today's news is certainly a setback, but it may just be a flesh wound.

Want to keep up to date on Cerus? Add it to your watchlist.

                                                                               

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Fool contributor Matt Koppenheffer does not own shares of any of the companies mentioned. You can check out what Matt is keeping an eye on by visiting his CAPS portfolio, or you can follow Matt on Twitter @KoppTheFool or on his RSS feed. The Fool's disclosure policy prefers dividends over a sharp stick in the eye.