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 MannKind (NASDAQ:56400P706), a biopharmaceutical company focused on the development of therapies to treat diabetes and cancer, sank as much as 17% after announcing a tentative date for the review of its inhaled diabetes medication, Afrezza, for the treatment of hyperglycemia.

So what: According to MannKind, it announced today before the opening bell that the Endocrinologic and Metabolic Drugs Advisory Committee had tentatively scheduled a review of Afrezza on April 1. The target date for the Food and Drug Administration to complete its review of Afrezza is April 15.

Now what: Following yesterday's romp higher without news, it's only befitting that skittish investors hit the exits today. The big news, of course, beyond just MannKind's volatility of late is that we're soon going to know the fate of inhaled diabetes drug Afrezza, which demonstrated solid efficacy in clinical studies, but was sent back to the drawing board twice since 2011. The memory of these two complete response letter rejections could very well be what's sending the stock lower today. With a completely redesigned inhaler, as well as positive clinical data, MannKind is now hoping for a different outcome. As for me, I do believe the third time could be the charm for MannKind, but I still have concerns with regard to the launch and pricing of the drug (if approved) relative to the current standard of treatment: insulin injection. Either way, you should have April 1 now circled on your calendars!