Take a look at some of Thursday's midday movers:
Alcoa - The aluminum producer gained after saying it would acquire aerospace-component maker Firth Rixson for $2.85 billion.
Barclays - U.S.-listed shares of the British bank fell sharply after New York Attorney General Eric Schneiderman announced a lawsuit against Barclays, accusing it of giving an unfair edge in the U.S. to high-frequency trading clients.
Read MoreBarclays claims of investor protection a 'sham': NY AG
Bed Bath & Beyond - The home retailer fell sharply a day after its first-quarter earnings missed estimates and it lowered its second-quarter outlook.
ConAgra Foods - The maker of Hunt's tomato ketchup and Slim Jim beef jerky rose after posting better-than-expected quarterly revenue.
GoPro - The wearable sports camera maker rallied nearly 30 percent in its market debut.
Iron Mountain - The storage and information management company jumped after the Internal Revenue Service approved its conversion into a real-estate investment trust.
Nabors Industries - The provider of drilling and rigging services rose after Guggenheim Securities upgraded its shares to "neutral" from "sell" and it agreed to merge one of its units with C&J Energy Services, shares of which fell.
Philip Morris International - The cigarette maker fell after reducing its guidance for the year.
ServiceMaster Global Holdings - The owner of residential and commercial property businesses gained in its trading debut.
—By CNBC's Kate Gibson.
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