Facebook - The social-networking company rallied after reporting better-than expected quarterly results, with Twitter also rising.
Tesla Motors - The electric-car maker gained after announcing teams of employees were driving across the country using the company's network of charging stations to power their batteries.
Neustar - The provider of technology and directory services plummeted on concerns it might lose a telecom-database contract held since 1997.
United Parcel Service - The package delivery company rose after reporting fourth-quarter profits that met expectations despite late deliveries during the holiday season. It also forecast a strong year ahead.
Alexion Pharmaceuticals - The biotech company's shares surged after it posted better-than-expected fourth-quarter profit on strong sales of its drug that treats rare genetic disorders.
Peabody Energy - The coal miner's shares fell after it reported a steeper-than-expected 14 percent decline in quarterly revenue due to weak steel and coal prices.
Harman International Industries - The audio-equipment maker's shares rose after it reported a 53 percent jump in second-quarter profit, helped by strong sales to luxury car makers.
Diageo - The world's biggest distilled drinks company dropped after it reported a slowdown in sales growth after demand dropped in China and other emerging markets.
Citrix Systems - The maker of cloud-computing software slid after forecasting current quarter and 2014 earnings below estimates.
Jos. A Bank Clothiers - The clothing retailer gained after Men's Wearhouse said it was considering raising its bid for its rival.
United States Steel - Shares of the steel maker rose after Macquarie upgraded the stock to outperform.
Caterpillar - The equipment maker climbed after entering a $1.7 billion accelerated stock-repurchase agreement with Citibank.
Pitney Bowes - The company's shares gained on better-than-expected fourth-quarter earnings.
(Read More: See CNBC's Market Insider Blog)
—By CNBC's Rich Fisherman.
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