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 Illumina (Nasdaq: ILMN) plummeted a staggering 30% today after the genetic analysis instrument maker projected current-quarter revenue well below expectations and suspended its full-year guidance.

So what: The whiff was so bad -- Illumina now sees third-quarter revenue of $235 million versus the average analyst estimate of $278 million -- that investors are being forced to seriously rework their growth assumptions. In fact, CEO Jay Flatley called the slump in new purchases "unprecedented," blaming it on slower upgrades, research-funding uncertainty, and simply a big drop in demand for its products.   

Now what: Don't expect things to turnaround anytime soon. "We expect these conditions to continue through at least the fourth quarter, while the 2012-2013 U.S. budgets for National Institutes of Health and other related agencies are determined," Flatley said. Of course, with rivals like Affymetrix (Nasdaq: AFFX) and Life Technologies (Nasdaq: LIFE) also getting pounded on the news, the entire space might be providing long-term investors with an enticing entry point.

Interested in more info on Illumina? Add it to your watchlist.