Pfizer - Shares of the drugmaker climbed after its pneumonia vaccine study met clinical objectives.
3D Systems - The maker of 3D printers fell after BofA/Merrill Lynch downgraded its shares to underperform from buy.
Trex - The deck maker gained after reporting better-than-expected fourth-quarter earnings.
Baidu - The Chinese internet company rose as did Autohome after Goldman Sachs upgraded both.
Sohu.com - Shares fell, as did those of Youku Tudou after Goldman Sachs downgraded both of the Chinese internet stocks.
Eli Lilly - Shares of the drug manufacturer rose after it said it would buy Germany's privately held Lohmann Animal Health for an undisclosed amount.
Hewlett-Packard - The technology company rose after Argus Research upgraded it to buy from hold.
Dillard's - The retailer fell after reporting weaker-than-expected fourth-quarter earnings.
Palo Alto Networks - The cybersecurity firm gained after posting better-than-expected second-quarter earnings.
Starz - Shares gained for a second session following the pay-network operator's fourth-quarter earnings report. Stifel Nicolaus upgrades the stock to hold from sell.
(Read More: See CNBC's Market Insider Blog)
—By CNBC's Rich Fisherman.
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