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 biopharma company MannKind (Nasdaq: MNKD) shed as much as 45% in intraday trading after the company revealed that the Food and Drug Administration did not approve its inhaled insulin treatment, Afrezza.

So what: This is now the second time that the FDA has declined to approve Afrezza, the first coming back in March of last year. This time around, the agency asked for two additional studies, including one that will compare the company's new inhaler to the previous version. MannKind's CEO, Alfred E. Mann, had been very optimistic about Afrezza and had his money where his mouth was, to the tune of hundreds of millions of dollars.

Now what: An analyst at Robert W. Baird called the FDA's response "the worst case scenario" and slapped a sell rating on the stock, noting that the company's decision to switch to the newer inhaler seemed like a risky move. Looking ahead, it certainly sounds as if the company is still committed to the drug and bringing the FDA a new round of data. Investors will probably want to skip this one, though thanks to the promise of more volatility, speculators may find reason to jump into the fray.

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