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 Santarus (UNKNOWN:SNTS.DL) surged nearly 40% today after fellow biotech Salix Pharmaceuticals (UNKNOWN:SLXP.DL) agreed to acquire it for about $2.6 billion.

So what: The all-cash deal values Santarus at $32 per share and represents a 37% premium to its closing price on Thursday. Salix is making the move to strengthen its leadership position in the gastroenterology drug market, and judging by its own stock's 16% pop today, Mr. Market is thrilled with the price that management is paying to do it.

Now what: Salix expects Santarus to be immediately and significantly accretive to earnings.

"We are very pleased to be able to merge our sales forces, combine two complementary product portfolios, expand our pipeline, diversify revenue, access health care providers in primary care, add a significant number of health care prescribers to our called-on universe and to better position Salix for success in the present as well as the future," said Salix CEO Carolyn Logan.

So while Santarus' upside is limited at this point, Salix's newly bolstered scale might be worth looking into.