Take a look at some of Monday's midday movers:
Exxon Mobil - Shares of the oil producer jumped nearly 3 percent after Goldman Sachs Group upgraded its rating of the stock to buy from neutral.
Monster Beverage - The distributor of carbonated-energy drinks climbed after RBC Capital Markets upgraded its shares to top pick from outperform.
American International Group - The insurer's shares gained in the wake of its agreement to sell its plane-leasing business to AerCap Holdings.
Cirrus Logic - Shares of the audio-chip supplier fell after Oppenheimer downgraded its stock to underperform from market perform.
Twitter - Shares of the social-networking site declined after Wells Fargo downgraded its stock to underperform from outperform. SunTrust Robinson cut Twitter to hold from buy.
Advanced Micro Devices - Shares of the semiconductor slid after Oppenheimer downgraded its stock to underperform from perform.
Universal Display - The provider of organic light-emitting diode technology jumped after JMP Securities reiterated its buy rating on its shares and hike its price target to $50 from $45.
Tiffany - Shares of the high-end jewelry seller rose after Canaccord Genuity upgraded its shares to hold from sell and upped its price target to $83 from $65.
Starwood Hotels & Resorts Worldwide - Shares of the resort operator rose after Nomura upgraded its stock to buy from neutral and raised its price target to $89 from $76.
Revolution Lighting Technologies - The maker of light-emitting-diode replacement lamps and fixtures rallied on news it had been awarded a U.S. Navy contract to supply LED lighting technology.
(Read more: See CNBC's Market Insider Blog)
—By CNBC's Kate Gibson.
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