iRobot - Shares of the robotics company surged after Raymond James upgraded the stock to a strong buy from market perform.
Facebook - The social-networking company rose after The Wall Street Journal reported Facebook would start selling video advertisements later in the week.
Frontier Communications - Shares of the regional telephone operator rallied after AT&T said it would sell its wireline operations in Connecticut to Frontier for $2 billion in cash.
Seagate Technology - Shares of the provider of electronic-data storage gained after JPMorgan upgraded its stock to neutral from underweight.
Williams Companies - Shares of the pipeline operator rose a day after Corvex Management said in a securities filing that it held an 8.82 percent stake in the company.
(Read More: See CNBC's Market Insider Blog)
—By CNBC's Kate Gibson.
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