Take a look at some of Tuesday's midday movers:
AbbVie - The drug manufacturer and Shire, the Irish company it agreed to purchase in July, both fell a day after the U.S. Treasury Department unveiled plans to curb tax-driven acquisitions. Medtronic and Covidien, the Irish medical supplier Medtronic is trying to acquire, also declined. Mylan and Abbott Laboratories dropped as well, two months after Mylan said it would buy Abbott's generic-drug business. And, Burger King Worldwide declined, less than a month after saying it would purchase Canadian doughnut seller Tim Hortons.
Allergan - The botox maker gained as it worked to finalize a deal to purchase Salix Pharmaceuticals to fend off a hostile offer from Valeant Pharmaceuticals International.
Apple - The iPhone maker climbed after S&P Dow Jones Indices released an analysis that found Apple had repurchased $5 billion of its stock in the second quarter.
CarMax - The used-car retailer dropped after reporting a lower-than-estimated quarterly profit.
Carnival - The cruise operator edged higher after posting a better-than-expected quarterly profit and hiking its 2014 outlook.
CF Industries Holdings - The fertilizer producer rose after it and Norway's Yara said in regulatory filings they were holding preliminary talks about a potential merger.
Galmed Pharmaceuticals - The biopharmaceutical company gained after saying the U.S. Food and Drug Administration had approved its request for a fast track designation of its candidate for the treatment of a form of hepatitis.
Herbalife - The nutrition company bounced back from losses the prior session as a tweet by Fox Business reporter Charles Gasparino capped speculation that billionaire Carl Icahn was selling his almost 19 percent stake in the company.
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