Amazon.com

(AMZN) - Get Report

was down 7.3% by late morning. As the online retailer unveiled another sales channel Wednesday, an influential

Robertson Stephens

analyst said the company risked overexpansion. Then today interactive television software maker

OpenTV

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said its filing with the

U.S. Patent Office

could restrict Amazon's rights to "one-click" technology. Another online bookseller,

Barnes&Noble.com

(BNBN)

, was up 3.6%.