Tessera Technologies Inc. says the U.S. agency investigating its patent infringement claims has affirmed that Tessera patents are valid _ but not that other companies have violated them.
The news sent Tessera shares down $2.38, or 10 percent, to $21.51 in premarket trading.
The company, which licenses miniaturization technology for electronics, has asked the U.S. International Trade Commission to bar imported products from several companies that it says violate its technology rights.
Tessera said late Tuesday that the ITC has issued a final ruling affirming the company's patents. But it said the agency did not find that Tessera proved infringement by other companies.
Those involved, mainly computer memory chip makers, include Acer Inc., Centon Electronics Inc., Elpida Memory Inc., Kingston Technology Co., Nanya Technology Corp., Powerchip Semiconductor Corp., ProMOS Technologies Inc., Ramaxel Technology Ltd., Smart Modular Technologies Inc. and TwinMOS Technologies Inc.
Tessera said it will appeal the decision.