The Dow Jones Industrial Average (DJINDICES:^DJI) has lost 31 points in pre-market trading, suggesting a negative start to the market today. World indexes ticked lower overnight, led by a 1% drop in Japan's Nikkei. European shares were off by 0.5% as of 8:30 a.m. EDT. 

Meanwhile, breaking news on Covidien (UNKNOWN:COV.DL) and DreamWorks Animation (NASDAQ:DWA) could spur heavy trading in both stocks today. 

Covidien's shares were up 29% in pre-market trading after the health-care technology giant agreed over the weekend to be purchased by Medtronic (NYSE:MDT).  The proposed deal is worth $43 billion and values Covidien's stock at roughly $93 a share. However, a big chunk of the purchase price will be delivered to Covidien shareholders in the form of Medtronic stock -- and that's making for some interesting pre-market action. Investors also bid up Medtronic's shares by 5.5%, which explains why Covidien's stock was already trading just above the announced purchase price. Medtronic said in a press release that this deal will create a medical tech and services company with almost $30 billion in annual sales and a massive global reach to over 150 countries. The merger should start kicking in higher cash earnings in fiscal 2016, with per-share earnings growth slated for 2018, according to Medtronic. 

Image source: DreamWorks.

DreamWorks Animation investors can breathe a sigh of relief. How to Train Your Dragon 2 opened to a solid $50 million in weekend receipts at the box office, which puts the animated film on track to beat the original movie's blockbuster $217 million domestic haul. While this weekend's opening wasn't as high as the $65 million that some analysts were targeting, it was far from a flop. And that win reverses an uncomfortable string of poor showings for DreamWorks: Mr. Peabody & Sherman last quarter joined 2013's Turbo and 2012's Rise of the Guardians as financial losers for the company. Audiences gave Dragon 2 high reviews (the film notched an A rating on CinemaScore), which should give it some staying power over the next few months. And a less crowded movie slate this summer means that the path is clear for the film to rack up some significant revenue for DreamWorks. The stock was down 6.8% in pre-market trading.