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 biopharmaceutical company Trius Therapautics (NASDAQ:TSRX) surged 20% today after larger peer Cubist Pharmaceuticals (NASDAQ:CBST) agreed to acquire it for up to $818 million.

So what: Cubist said it will pay $13.50 per share in cash for Trius and a $2.00 per share bonus if Trius meets certain sales targets, with the collective $15.50 offer representing a 32% premium to Trius' closing price on Tuesday. Cubist is buying Trius along with Optimer Pharmaceuticals (UNKNOWN:OPTR.DL) to strengthen its position in antibiotics, and judging by Cubist's 10% pop today, Mr. Market is pleased with the price it's paying to do it.

Now what: Cubist expects the transaction to close later this year, subject to required regulatory approvals and other customary closing conditions.

"Trius is a tremendous strategic fit with Cubist that supports our Building Blocks of Growth long-range goals while extending our global leadership in the acute care environment," said Cubist CEO Michael Bonney. "Tedizolid is an exciting late-stage antibiotic candidate that we believe has the potential to be an important new tool in the infectious disease community's battle against resistant infections caused by MRSA."

So while Trius is likely all popped out at this point, Cubist's expanded presence in the increasingly attractive antibiotics space is certainly worth looking into.    

Fool contributor Brian Pacampara has no position in any stocks mentioned. The Motley Fool recommends Cubist Pharmaceuticals. 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.