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 cardiovascular-focused biopharmaceutical company Amarin (Nasdaq: AMRN) rallied as much as 19.5% today after a competitor released disappointing drug data.

So what: One company's pain is another company's gain, and we're seeing this in action today. Omthera Pharmaceuticals released late-stage study results on its omega3 drug, Epanova, last night and the data appear to show that it works less effectively than Amarin's AMR101. The data would put Epanova on par in effectiveness with GlaxoSmithKline's (NYSE: GSK) Lovaza, which is the only prescription-grade omega3 medication currently approved by the FDA.

Now what: The news appears to clear the way for AMR101 to potentially gain best-of-breed status in this drug class, if it can get approved. This also brings into question whether Amarin will be able to compete against Glaxo's significantly larger marketing budget. Ultimately, today's news is bullish for shareholders and the company deserves a spot on My Watchlist in the meantime because of this turn of events.

Craving more input? Start by adding Amarin 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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