Yahoo —The Internet giant's shares are under pressure after China's Alibaba — partly owned by Yahoo —showed that revenue growth had slowed for the year ending March 31.

Fusion-IO – The maker of flash-based hardware and software is being bought by SanDisk for $1.1 billion in cash, or $11.25 per share.

Covidien —The Ireland-based medical products maker agreed to be bought by U.S.–based Medtronic for $42.9 billion in cash and stock.

Check out which companies are making headlines before the bell:

Pinnacle Foods–Hillshire Brands has officially withdrawn its recommendation to shareholders that it approve the previously struck deal to buy Pinnacle. Hillshire instead is moving towards completion of its own deal to be bought by Tyson Foods.

Target–The retailer experienced problems with its computerized checkout systems in some states over the weekend, although the company said the problem was not related to any security issue.

Bluebird Bio–The drug maker reported positive data on its gene therapy treatment for a blood disorder known as beta-thalassemia. The treatment allowed patients to go several months without receiving blood transfusions, which are often frequently required in people who suffer from the disorder.

Dish Network–The satellite TV operator's shares were upgraded to "overweight" from "neutral" at JPMorgan Chase, which said it sees many possible drivers for a higher stock price.

AT&T– The telecom giant said some AT&T Wireless customers had their accounts hacked between April 9 and April 21, although it did not say how many customers were affected. The company is offering all its customers a year of free credit monitoring.

Williams Companies–Williams will pay almost $6 billion in cash to buy the 50 percent of Access Midstream Partners that it didn't already own. The energy producer wants to increase its presence in major shale areas.

International Game Technology–IGT is in preliminary talks to be acquired by Italy-based lottery operator GTECH, which said in a statement that it had hired advisers for the potential deal. In its own statement, IGT said it regularly explores strategic alternatives and "is currently engaged in such an exploration," although it did not mention GTECH by name.

Google–The technology behemoth could see its Skybox acquisition have a bigger positive impact on earnings than many other recent tech acquisitions, according to an article in the Wall Street Journal.

United Continental, American Airlines Group, Delta, Southwest – Airline stocks could be impacted today as the price of crude rises to its highest in nine months.

Capital One–The company has reportedly agreed to use its consumer database only to bar potential customers who have engaged in fraud. he New York Times said the deal stems from a probe by New York attorney general Eric Schneiderman, who has been looking into whether banks are improperly denying or restricting banking access to New York consumers.

General Electric–Germany's Siemens and Japan's Mutsubishi Heavy Industry are expected to present their bid for some of the businesses owned by France's Alstom today, which could raise the pressure on GE to increase its own Alstom bid.

AK Steel – Bank of America/Merrill Lynch upgraded the steelmaker's shares to "buy" from "neutral."

—By CNBC's Peter Schacknow

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