Take a look at some of Friday's midday movers:
Alibaba Group Holding - The Chinese online retailer surged in its U.S. trading debut after raising nearly $22 billion in an initial public offering.
American Eagle Outfitters - The teen-focused retailer edged up after Goldman Sachs raised its rating to buy from neutral.
Apple - The consumer-technology provider fell as it started selling its latest iPhones in stores around the country.
CARBO Ceramics - The provider of oilfield-services technology fell after Goldman Sachs cut its rating on the stock to sell from neutral.
Caterpillar - The maker of construction equipment dropped after saying in a regulatory filing year-over-year sales of global equipment declined 10 percent from June to August.
Glu Mobile - The mobile-games company declined after saying in a regulatory filling it would sell nearly 10 million shares.
ITT Educational Services - The for-profit educator plummeted after saying in a regulatory filing the Securities and Exchange Commission could take enforcement action against it over its student loans.
Rockwell Collins - The maker of aircraft engines advanced after projecting 2015 profit and sales above expectations.
SeaDrill - The rig company dropped after a top executive quit the board of the Norwegian company.
Yahoo - The online-search engine fell as it sold part of its holdings in Alibaba.
Zions Bancorp - The regional bank edged higher after Raymond James upgraded its stock to a strong buy from outperform.
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—By CNBC's Rich Fisherman.
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