Take a look at some of Thursday midday movers:
Apple moved higher after billionaire investor Carl Icahn, in a public letter, called on CEO Tim Cook to start an immediate tender offer of $150 billion at $525 per share.
Stryker moved lower after the medical device maker agreed to pay $13.2 million to settle civil bribery charges that alleged the company bribed doctors and government officials to win business in five foreign countries.
McKesson moved higher after the company said it would buy German rival Celesio for about $8.3 billion, including debt. The drug distributor also posted better-than-expected third-quarter earnings and raised its full-year outlook.
International Paper gained after posted better-than-expected third-quarter earnings, helped by strong sales of corrugated packaging for shipping boxes.
Goldman Sachs rose after Deutsche Bank upgraded the investment bank to "buy" from "hold" with a price target of $181 a share, citing valuation.
Deutsche Bank also upgraded US Airways to "buy" from "hold" with a price target of $30 a share, citing improving fundamentals.
Arctic Cat fell after the maker of snowmobiles and ATV's posted weaker-than-expected profit and said its full -ear results would be at the low end of its range.
Royal Caribbean moved higher after the cruise ship operator raised its full-year earnings forecast amid improvement in ticket sales in Europe.
Timken lost ground after the steel products maker said third quarter profit dropped 35 percent on weaker revenue.
Canadian gold miner Agnico Eagle Mines rose after reporting better than expected third-quarter earnings, even as profits fell 56 percent on lower metal prices. The company also increased production guidance for 2013.
RR Donnelly & Sons jumped after agreeing to buy fellow printing company Consolidated Graphics in a cash-and-stock deal worth $620 million, or $62 a share, a 2.5 percent discount from Consolidated's closing price on Wednesday.
Hershey lost ground as the chocolate maker's sales rose less than expected.
Mead Johnson fell despite reporting a 15 percent gain in quarterly profit while raising its full-year earnings forecast. The maker of Enfamil baby formula also said it had launched its own investigation into alleged price fixing buy its Chinese unit. It said it was complying with requests from the SEC for information on the matter.
Natus Medical gained on news the company swung to a third quarter profit on better than expected results in its neurology and newborn care units. As a result, the company raised its full-year guidance.
Tractor Supply jumped after reporting a 31 percent rise in earnings that easily beat Wall Street estimates.
—By CNBC's Rich Fisherman.
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