McDonald's - The fast-food chain slid after reporting global sales dropped more than expected in July.
Medivation - The drug maker gained after hiking its full-year U.S. sales forecast for its prostate cancer drug.
Mercadolibre - The eBay of Latin America moved higher after posting better-than-expected quarterly earnings.
Mylan - The maker of generic drugs fell after RBC Capital downgraded its shares.
Post Holdings - The cereal maker dropped after cutting its earnings outlook for the year.
Salix Pharmaceuticals - The drug company dropped after reporting weaker-than-expected quarterly results.
Sotheby's - The auctioneer declined after tallying weaker-than-expected second-quarter results.
Tekmira Pharmaceuticals - The Canadian biotech firm surged after the Federal Drug Administration cleared its experimental Ebola drug for potential use.
Volcano - The medical-equipment maker fell after Oppenheimer downgraded the stock to market perform from outperform.
(See CNBC's Market Insider Blog)
—By CNBC's Rich Fisherman.
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