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 11% today after its quarterly results and outlook impressed Wall Street.

So what: Biogen shares had slipped in recent weeks on nervousness heading into the quarter, but strong Q2 results -- income surged 46% to $714.5 million on a revenue jump of 40% -- coupled with upbeat full-year guidance are quickly easing those concerns. In fact, sales of the company's newest MS treatment, Tecfidera, more than tripled to $700 million with $115 million of that figure coming from outside of the U.S., giving analysts plenty of good vibes over the drug's global growth trajectory going forward.

Now what: Management now sees full-year adjusted EPS of $12.90 to $13.10 a share, up nicely from its prior view of $11.45. "We remain focused on additional potential approvals and pivotal read-outs, and continue to look to increase investment in early stage research to broaden and advance our neurology, immunology and hematology pipelines," said CEO George Scangos, Ph.D. Of course, with Biogen shares now up about 70% from their 52-week lows and trading at a 20-plus forward P/E, I'd hold out for a wider margin of safety before buying too heavily into those prospects.