Take a look at some of Tuesday's midday movers:
Affiliated Managers Group - The asset manager soared on better-than-expected first-quarter earnings.
Alliant Techsystems - The ammunition maker rose after saying it would merge with rocket maker Orbital Sciences.
Amicus Therapeutics - The drug developer rose after saying its drug to treat fat-storage disorder was found effective in a late-stage trial.
Apple - The consumer technology company fell a bit after projecting strong demand for its new bond issue.
Boston Scientific - The medical device maker fell after reporting quarterly revenue slightly below expectations.
CIT Group - The bank holding company fell on weaker-than-expected first-quarter earnings.
Exxon Mobil - The oil producer hit a 52-week high, as did Schlumberger, ConocoPhilips, Oneok and Consol Energy.
Goodyear Tire & Rubber - The tire supplier declined after reporting lower-than-expected quarterly revenue.
Hewlett-Packard - The technology company rose after Pacific Crest upgraded the stock to outperform and set a $37 price target.
MGM Resorts International - The casino operator climbed after its first-quarter net income soared. Wynn Resorts and Las Vegas Sands also advanced.
NorthStar Realty Finance - The real estate financing company fell and American Realty Capital Properties rose after they said they were not currently in merger discussions.
Novartis - The pharmaceutical company advanced after JPMorgan upgraded the stock to overweight from neutral.
3D Systems - The printing company slid after reporting first-quarter earnings that matched street expectations.
TRW Automotive Holdings - The auto parts supplier fell after better-than-expected first-quarter earnings.
Sprint - The wireless carrier gained after posting a narrower-than-expected first-quarter loss.
Walgreen - The drugstore chain edged lower as hedge fund JANA Partners said it had taken a new position in the company last quarter. Jana also announced a new position in AerCap Holdings last quarter.
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—By CNBC's Rich Fisherman.
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