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 Regeneron Pharmaceuticals (NASDAQ:REGN), a biopharmaceutical company developing therapies to treat serious medical conditions, jumped as much as 13% after the company's CEO announced initial sales projections for Eylea in the fourth quarter and following the announcement of a new treatment under development in partnership with Bayer (OTC:BAYRY).

So what: According to comments from Regeneron CEO Len Schleifer at the JPMorgan Healthcare Conference, the company anticipates reporting $400 million in U.S. sales of Eylea, its wet age-related macular degeneration drug, in the fourth quarter. Furthermore, Schleiifer sees plenty of opportunity for future growth of the drug in U.S. and European markets. In addition to this news, after the closing bell yesterday Regeneron and Bayer announced the joint development of a new treatment option for wet-AMD, a PDGFR-beta antibody that Regeneron will have rights to in the U.S. and Bayer will control throughout the rest of the world. The pact includes a $25.5 million up-front payment to Regeneron, as well as the potential to earn $40 million in option and milestone payments.

Now what: Regeneron's Eylea is simply unstoppable. Not even the holidays seemed to slow sales down much. Obviously, sales can't move higher in an exponential fashion and longtime users of the drug will need fewer injections, but Eylea is still just touching the tip of the iceberg in terms of its sales potential, especially in overseas markets. I still, personally, have a difficult time dealing with Regeneron's forward P/E of 54, but its top-line growth and margin momentum could be enough to sustain its share price around $300.