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 developer Amylin Pharmaceuticals (Nasdaq: AMLN) were soaring today, gaining as much as 21% in intraday trading as investors reacted to the U.S. Food and Drug Administration's approval of the company's diabetes treatment.

So what: Trading in Amylin shares was halted on Friday as the decision deadline approached, so this morning was the first opportunity that investors had to react in non-after-hours trading to the good news.

With the approval, Bydureon will be the first, once-per-week treatment for type 2 diabetes to hit the market. The FDA's thumbs-up follows an extended approval process, which included extra testing to address safety concerns. In the end, the FDA is requiring that the prescribing label for the drug include a warning about the fact that it caused certain types of thyroid tumors in rats.

Now what: For Amylin shareholders, the focus now turns to how the drug will be received by the market. The drug addresses a massive market in the U.S. and, at least from a perspective of convenience, the once-per-week formulation is a notable selling point. However, other drug manufacturers have hardly overlooked the diabetes market and so Bydureon faces, and will continue face, significant competition.

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