Take a look at some of Monday's midday movers:
Alexion Pharmaceuticals - The biopharmaceutical company fell after reporting second-quarter results.
Cummins - The engine maker declined after the midpoint of its full-year revenue guidance missed consensus estimates.
D.R. Horton - The home builder and competitors including Lennar and PulteGroup fell after data showed an unexpected drop in pending home sales in June.
Family Dollar Stores - Shares of the discount retailer surged after competitor Dollar Tree said it would buy the company for $8.5 billion.
First Solar - The solar-panel manufacturer rose after releasing a statement saying it had reached a deal to supply 100 megawatts of modules a year to XSOL for projects in Japan.
Tyson Foods - The meat processor gained after saying it would sell its Mexican and Brazilian poultry businesses for $575 million.
Zillow - The real estate website declined after saying it would acquire rival Trulia for $3.5 billion in stock.
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—By CNBC's Kate Gibson.
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