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 molecular diagnostic company Cepheid (Nasdaq: CPHD) have been spliced and diced today, falling as much as 24%, after it reported weaker-than-anticipated earnings results.

So what: For the second quarter, Cepheid reported revenue growth of 21% and net income of $0.02, down slightly from the $0.03 it reported last year. The impetus for the cliff dive, however, was based on Cepheid's forward-looking forecast. The company lowered its full-year profit forecast to a range of $0.38-$0.42 from its previous guidance of $0.50-$0.55, which it blamed on a mixture of higher costs associated with rolling out its products in developing countries, longer order cycles ahead of the U.S. elections, and unfavorable currency volatility.

Now what: Cepheid wasn't a cheap company in the first place, and following today's drop it's still not inexpensive. Still, Cepheid does offer the revolutionary GeneXpert diagnostic system, which has the potential to make the company extremely profitable -- assuming it can stay out of its own way. Cepheid's current concerns aren't likely to abate in just one quarter, so I wouldn't be clamoring to buy in here after today's drop, but it's definitely a company to keep on your Watchlist if it continues to trade lower.

Craving more input? Start by adding Cepheid to your free and personalized Watchlist so you can keep up on the latest news with the company.

Fool contributor Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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