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 defibrillation and CPR-gear specialist Zoll Medical (Nasdaq: ZOLL) climbed as high as 10.1% today on fairly big trading volume.

So what: This stock plunged face-first on Monday because of a dire new risk outlined in the freshly filed 10-Q: LifeVest products might not get the wide market access they were expected to gain. Today, Zoll executives took part in a conference call arranged by Jefferies to calm frazzled investor nerves -- and it looks like that worked to some degree.

Now what: I don't know what was said during that fateful call, but the bulk of today's climb started along with the phone action and ended when they hung up. Whatever the message -- nitpicked by a supposedly independent doctor selected by Jefferies -- ZOLL is still set to close the week some 22% lower. And before writing that off as just getting caught in the general market panic, consider that sector rivals Medtronic (NYSE: MDT), CONMED (Nasdaq: CNMD), and Boston Scientific (NYSE: BSX) all dropped about half as far. On the other hand, ZOLL investors have already ridden the LifeVest to 86% gains over the last year.

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