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 Furiex Pharmaceuticals (UNKNOWN:FURX.DX), a biopharmaceutical company developing drugs to treat a myriad of problems including irritable bowel syndrome, acute bacterial skin and skin structure infections, and type 2 diabetes, more than doubled, gaining as much as 165%, after reporting positive results from its two late-stage studies of eluxadoline for patients with diarrhea-predominant irritable bowel syndrome.

So what: According to the company's press release, top-line results from its two studies demonstrated that eluxadoline met the primary endpoints agreed upon by the Food and Drug Administration and European Medicines Agency of simultaneous improvements in stool consistency and abdominal pain. Stool consistency improved across its two studies by 30% to 37% compared to just 20% to 22% for the placebo, although one of its 75 mg studies failed to meet statistical significance. Eluxadoline was also well-tolerated in trials, and Furiex plans to file a new drug application with the FDA in the second quarter. Research firm Ladenburg Thalmann also boosted its price target to $137 from $58 on the news.

Now what: "Wow" is all I can say after the run we've witnessed in Furiex today! The peak sales potential of eluxadoline according to Canaccord Genuity is $745 million, so today's move higher does actually value Furiex appropriately... if the drug were without question approved and Furiex was partnered with a leading pharmaceutical company. However, there are a lot of variables left to play out here, including the FDA's ultimate decision on eluxadoline and how successfully Furiex can market its drug compared to existing treatments. I'm not in any way saying Furiex doesn't deserve to be up big today, but this move may wind up being a bit excessive when all is said and done.

Furiex's move higher is astounding -- but even it may struggle to keep pace with this top stock in 2014
There's a huge difference between a good stock and a stock that can make you rich. The Motley Fool's chief investment officer has selected his No. 1 stock for 2014, and it's one of those stocks that could make you rich. You can find out which stock it is in the special free report "The Motley Fool's Top Stock for 2014." Just click here to access the report and find out the name of this under-the-radar company.

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.

Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.