Varonis Systems - Shares of the provider of software that controls human-generated enterprise data surged in its market debut.
Orbitz Worldwide - Shares rose after the online travel company said it would acquire certain assets from Travelocity.
Riverbed Technology - The manufacturer of network gear fell after it rejected Elliott Management's raised bid of $3.4 billion, calling the hedge fund's offer too low.
Men's Wearhouse - Shares of the men's clothiers rose after Jos. A. Bank Clothiers rejected its $1.78 billion offer, but said it was willing to meet with its larger rival to talk about a higher bid.
3D Systems - The maker of 3D printers rose after predicting $1 billion in revenue in 2015.
Mercadolibre - Shares rose after the host of online commerce platforms in Latin America reported better-than-expected fourth-quarter results.
Medivation - Shares of the drug manufacturer declined after it projected less-than-expected revenue from its prostate cancer treatment Xtandi in 2014.
Madison Square Garden - The owner of the New York Knicks and Radio City Music Hall fell after Bloomberg News cited people with knowledge of the matter in reporting MSG CEO Hank Ratner was being replaced by Tad Smith, president of local media for Cablevision Systems.
MEI Pharma - Shares climbed after it said the U.S. Food and Drug Administration had granted orphan drug status for its treatment of acute myloid leukemia.
OmniVision Technologies - The maker of image-sensor devices gained after reporting third-quarter earnings that easily beat street views.
Endologix - Shares fell in 10 times its normal trading volume after the medical device maker forecast its slowest annual revenue growth in a decade for 2014.
(Read More: See CNBC's Market Insider Blog)
—By CNBC's Rich Fisherman.
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