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 Sequenom (Nasdaq: SQNM) sank as low as 10% on Friday after health insurer Coventry Health Care (NYSE: CVH) changed its mind about providing coverage for the company's prenatal Down syndrome test.

So what: Coventry was going to provide coverage to its 2.2 million members for Sequenom's MaterniT21 PLUS testing service, so the termination is naturally forcing investors to lower their revenue expectations. Of course, given that Coventry is one of the smaller companies in the health-insurance space, the loss shouldn't be too devastating to Sequenom's top line.

Now what: Aggressive bargain hunters might want to take a closer look. As William Blair analyst Brian Weinstein pointed out in a note to investors, Sequenom still expects to gain coverage for MaterniT21 PLUS from two of the six largest health insurers by the end of the year, making today's pullback a potentially profitable entry point for enterprising investors. Of course, given the company's consistent money-losing history, risk-averse conservative-types might want to maintain their distance.

Interested in more info on Sequenom? Add it to your Watchlist.

Fool contributor Brian Pacampara owns no position in any of the companies mentioned. Motley Fool newsletter services have recommended buying shares of Coventry. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Fool's disclosure policy always gets a perfect score.