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 ABIOMED (NASDAQ:ABMD), a maker of heart support devices, are being absolutely crushed, falling as much as 33% earlier in the trading session, after reporting its second-quarter earnings results.

So what: Surprisingly, ABIOMED's plunge has very little to do with the actual earnings figures themselves -- which came in higher than Wall Street's estimates on an EPS basis -- and almost everything to do with a statement buried beneath its earnings results. In its filing, ABIOMED notes that on Oct. 26, it was informed by the U.S. Attorney's Office for the District of Columbia that it was investigating the company's marketing and labeling practices surrounding its lead revenue-generating device, the Impella 2.5, which pulls blood from the left ventricle of the heart through a catheter, and sends it into the ascending aorta. ABIOMED has pledged to cooperate fully with the investigation.

Now what: The real concern here is that its Impella devices are its primary growth driver. ABIOMED's annual revenue forecast calls for growth of 23%-24%, of which Impella sales are forecast to grow in excess of 30%. If ABIOMED is somehow found guilty of violating marketing or labeling practices, that could cripple its growth prospects. As usual, ABIOMED is innocent until proven guilty but, even after today's tumble, it's still trading at a frothy 32 times forward earnings. This is a case of neat technology, but little substance to the bottom line thus far.

Craving more input? Start by adding ABIOMED 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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