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 biotechnology company United Therapeutics (NASDAQ:UTHR) took a long walk off a short plank, falling as much as 15% after announcing the receipt of an unfavorable complete response letter for its oral new drug application, or NDA, Remodulin.

So what: In today's CRL, the Food and Drug Administration questioned whether oral Remodulin slowed the progression of pulmonary arterial hypertension, a condition that causes blood vessels leading to the lungs to narrow, putting excess stress on the heart and boosts blood pressure. The FDA questioned the significance of its six-minute walk test as well. The FDA didn't state whether or not altering the parameters of United Therapeutics' testing would change the results and eventually lead to an approval of the oral drug, but it did suggest a fixed dosing and more frequent dosing regimen.

Now what: You don't often hear me say this, but today's move lower seems perfectly justified. Not a gigantic overreaction to an FDA rejection, but enough to wipe out the potential for oral Remodulin. What's worth keeping in mind is that United Therapeutics is a lot more than just one failed NDA. Even without oral Remodulin, the company is valued at a mere nine times forward earnings and should be able to grow sales by low single-digits next year. It'll merit a deeper dive, but on the surface, United Therapeutics' could be a bargain following today's swan dive.

Craving more input? Start by adding United Therapeutics to your free and personalized watchlist so you can keep up on the latest news with the company.

Fool contributor Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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