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 company VIVUS (NASDAQ:VVUS) climbed 10% today after its obesity pill prescriptions impressed Wall Street.

So what: The stock has slumped in recent months on initial slow sales of its new obesity drug Qsymia, but today's numbers suggest that the pill is finally starting to gain traction. VIVUS said it shipped 12,978 prescriptions of Qsymia in the four weeks ended Dec. 21, representing a 68% spike from the preceding period, reigniting optimism over the drug's blockbuster potential.

Now what: I'd expect the prescription momentum to remain positive. Qsymia's initial ramp-up was weighed down by a lack of insurance reimbursements, but with recent new coverage from the likes of Aetna (NYSE:AET) and Express Scripts (NASDAQ:ESRX), the company's long-term sales prospects are certainly looking better. So while VIVUS might still be too speculative for average investors, VIVUS' brightened picture makes it an interesting pick for biotech-savvy Fools.

Fool contributor Brian Pacampara has no position in any stocks mentioned. The Motley Fool recommends Express Scripts. The Motley Fool owns shares of Express Scripts. 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.