7:25 AM -- A tough week got a little worse Thursday for Nokia Networks (NSN) when its German parent wrote down the value of its holding in the telecom equipment firm. (See NSN Hopes Dashed as Ciena/Nortel Deal OK'd.)

Siemens AG (NYSE: SI; Frankfurt: SIE) reported a fourth-quarter net loss of €1.063 billion (US$1.61 billion) today following a non-cash impairment charge of €1.634 billion ($2.47 billion) against the value of its 50 percent stake in NSN.

The German industrial giant's quarterly deficit also included a €328 million ($496 million) loss as a result of its stake in NSN.

Siemens is the co-owner of NSN along with Finnish giant Nokia Corp. (NYSE: NOK), which also recently announced a non-cash impairment charge against the value of its stake. (See No Sign of Recovery for Nokia Siemens.)

NSN CEO Rajeev Suri has committed the vendor to an improved financial performance in 2010. He told Attendees at Nokia's Capital Markets Day Wednesday that NSN will increase its market share next year even though the value of the telecom infrastructure and associated services market promises to remain flat. (See NSN CEO: Don't Write Our Obituary.)

— Ray Le Maistre, International News Editor, Light Reading