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 biotech giant Biogen Idec (Nasdaq: BIIB) surged 20% in intraday trading Thursday after releasing positive data on its experimental multiple sclerosis drug, BG-12.

So what: In a clinical trial, BG-12 was shown to be highly effective for the very first time, which certainly boosts Biogen's position in the attractive, yet increasingly competitive, market for oral MS drugs. In fact, based on the initial data, BG-12 appears to be more effective than Teva Pharmaceutical's (Nasdaq: TEVA) own oral MS pill, laquinimod, prompting Mr. Market to send Teva's shares down more than 6% today.

Now what: Don't let today's big rally keep you from looking into the stock. Lost in the BG-12 hubbub were Biogen's first-quarter profit growth of 35%, which easily topped Wall Street estimates, and the reaffirmation of its strong full-year outlook. When you add BG-12's blockbuster potential to an already solidly performing multiple sclerosis portfolio, Biogen seems like a relatively solid biotech bet.

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Fool contributor Brian Pacampara owns no position in any of the companies mentioned. Teva is a Motley Fool Global Gains pick, and the Fool owns shares of it. Try any of our Foolish newsletter services free for 30 days.

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