Take a look at some of Monday's midday movers:
Amazon.com - The online retailer edged higher after saying it would let users shop via Twitter. In addition, Twitter's six-month lockup that prevents early investors from selling their shares, ends Monday.
Aaon - The maker of heating and air-conditioning equipment rose after reporting first-quarter revenue that beat estimates.
Bank of America - The lender fell two days ahead of its shareholder meeting.
Blackberry - The wireless device maker fell to a 52-week low after agreeing to sell the majority of its Canadian real estate holdings to Spear Street Capital for $278 million.
B/E Aerospace - The manufacturer of airplane components climbed after saying it might put itself up for sale.
Goldman Sachs Group - The brokerage fell after a proxy advisory firm recommended shareholders vote against its executive compensation plan. It added that Morgan Stanley was also paying its executives too much.
King Digital Entertainment - The game maker gained after the three lead underwriters of its IPO started coverage of the stock with a buy rating or the equivalent.
Nordion - The Canadian medical isotope supplier rose after Sterigenics, a sterilization services provider, upped its offer after Nordion drew a competing bid from an unnamed entity.
PerkinElmer The maker of medical equipment rose after Janney upgraded it to buy.
Plug Power The provider of hydrogen fuel cells used to run equipment including forklifts fell after tripping a Nasdaq short sale circuit breaker.
Sotheby's - The auctioneer rose after agreeing to add three members to its board, including activist investor Daniel Loeb.
Target - The discount retailer fell after removing Chairman and Chief Executive Gregg Steinhafel in the wake of the massive data breach late last year.
Walgreen The drugstore chain advanced after reporting better-than-expected same-store sales in April.
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—By CNBC's Rich Fisherman.
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