Take a look at some of Tuesday's midday movers:
McDonald's - The fast-food chain jumped 3.3 percent after its CFO told an investor conference the company was looking at ways of returning more cash to shareholders.
Herbalife - Shares of the supplement seller dropped 1.7 percent after billionaire Bill Ackman said he would unveil details about the company's alleged violations Tuesday afternoon during a presentation in China.
Senomyx - Shares surged 28 percent after the FDA designated its sweetener enhancer safe, allowing beverage makers to add it to products to reduce the use of sugar or sugar substitutes.
American Eagle Outfitters - Shares declined 5.2 percent after the teen-apparel retailer forecast earnings for the current quarter below street expectations.
Myriad Genetics - Shares lost 9 percent ground after it said a U.S. District Court in Utah denied a motion to stop rival Ambry Genetics from selling a similar version of Myriad's genetic-susceptibility test for breast cancer.
General Motors - Shares fell 2.4 percent after a Senate aide, who asked not to be identified, told Reuters the Senate Commerce Committee is looking to hold hearings on the auto manufacturer's recalls related to ignition switch problems.
CBS - dropped 0.8 percent after the network's CEO said CBS might offer its content directly to consumers over the Internet and cut its traditional broadcast signal if the Aereo video-streaming service is found to be legal.
EBay - The e-commerce company fell 0.1 percent. CEO John Donahoe's compensation in 2013 fell 53 percent from the prior year, according to a regulatory filing.
Las Vegas Sands - Shares rose 0.3 percent after a strong start in March gaming revenue in Macao. Other casino operators also gained, with Wynn Resorts up 0.9 percent. MGM Resorts International fell 0.7 percent.
Douglas Dynamics - Shares of rose 2.5 percent after the maker of ice-control equipment for light trucks reported better-than-expected fourth-quarter results.
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—By CNBC's Rich Fisherman.
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