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 biotech company MannKind (Nasdaq: MNKD) plummeted more than 20% in intraday trading Friday after the company posted a fourth-quarter loss and said it would lay off 179 workers, or about 40% of its staff.

So what: With its lead inhaled-insulin product Afrezza now having been rejected twice by the Food and Drug Administration, MannKind is naturally seeking to conserve cash as it continues to strive for that ever-elusive approval. Unfortunately, Afrezza's recent struggles also prompted management to terminate its human insulin supply agreement with Merck (NYSE: MRK), costing MannKind an additional $22.7 million in termination fees.

Now what: I'd be really cautious about pouncing on today's plunge. While MannKind's distress isn't exactly a big surprise to many Fools, founder and CEO Al Mann's continuous capital backing has always been something die-hard bulls could count on. But with Mann stating on the conference call that he "can't make any commitments at this point," it's tough to understand why individual investors would.

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Fool contributor Brian Pacampara owns no position in any of the companies mentioned. Try any of our Foolish newsletter services free for 30 days.

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