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 Covidien plc (COV.DL) surged 20% today after medical device giant Medtronic (MDT -1.74%) agreed to acquire its rival for $42.9 billion.

So what: The cash-and-stock deal --$35.19 in cash and 0.956 of a Medtronic share -- values Covidien at $93.22 per share and represents a premium of 29% to its closing price on Friday. Medtronic is making the move to increase its global reach and significantly boost scale but, judging by its own stock's 2% decline today, Mr. Market isn't too thrilled with the price that management is paying to do it.

Now what: The transaction is expected to be accretive to Medtronic's cash earnings and GAAP earnings in FY 2016 and FY 2018, respectively. "This acquisition will allow Medtronic to reach more patients, in more ways and in more places," said Medtronic Chairman and CEO Omar Ishrak. "Our expertise and portfolio of services will allow us to serve our customers more efficiently and better address the demands of the current health care marketplace. We also look forward to welcoming the Covidien team to Medtronic and working together to improve health care outcomes globally." So while Covidien is likely all popped out at this point, Medtronic's newly bolstered top and bottom line growth prospects might be worth looking into.