Take a look at some of Friday's midday movers:
Cliffs Natural Resources - The iron-ore miner fell after Nomura cut its rating to "reduce" from "buy."
Covidien - The Irish drug manufacturer rose after Medtronic said it would use $16 billion in outside financing to fund the cash part of the medical-technology provider's nearly $43 billion deal for Covidien.
Diamond Offshore Drilling - The provider of oil-drilling services led losses on the , falling along with the price of crude. Competitors including Noble, Transocean and Chesapeake Energy also declined.
General Motors - The vehicle manufacturer rose after telling dealers to halt deliveries of new mid-sized pickup trucks due to issues related to air bags.
Media General -The television-station operator spiked after Gabelli & Co. upgraded its shares to "hold" from "buy."
Mylan - The generic drug maker rallied after hiking its forecast for the third quarter and year.
Salix Pharmaceuticals - The drug developer gained after pulling the plug on its purchases of Cosmo Technologies.
Yodlee - The maker of financial software jumped in its market debut.