Take a look at some of Tuesday's midday movers:
Biogen Idec - The drug developer rose after reporting positive trial data from its experimental Alzheimer's drug.
Priceline Group - The online travel site fell after FBR downgraded the stock to market perform from outperform.
BP - The oil company gained amid chatter of a takeover bid from Royal Dutch Shell. Both companies declined comment.
General Motors - The auto manufacturer rose, as did competitors including Fiat Chrysler, Ford Motor and Toyota Motor after all four reported better-than-expected November sales.
Eli Lilly - The drug company climbed after saying it entered an exclusive agreement to develop privately held biopharmaceutical firm Zosano Pharm's experimental treatment for severe osteoporosis.
RadioShack - The electronics retailer was halted after rejecting claims from its lender of a covenant breach.
Legg Mason - The asset manager fell after activist investor Nelson Peltz resigned from its board.
Bank of New York Mellon - The trust bank gained after saying it added the co-founder of investment firm Trian Fund to its board.
Apache - The energy explorer edged lower after Mizuho downgraded its shares to neutral from buy.
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