Seven reported that Unwired's earnings before tax for the half-year was a loss of $15 million.
Seven also reported depreciation in Unwired's assets of $15.8 million and wrote down Unwired's value to the tune of $35.2 million.
"The overall declines in the share market and the re-assessment of market values for spectrum licenses have resulted in an impairment of $35.2 million," the company said in an ASX statement.
Seven paid $135.6 million for the company in November 2007 but is yet to do much with the investment.
Unwired is still operating its wireless broadband network on a pre-WiMAX standard.
"The technical assessment of the WiMAX network has been completed and Seven Network Limited is currently investigating funding arrangements for the deployment of this network," the media company said.
"We have a firm belief in the future of our spectrum and the introduction of WiMAX and we'll likely be developing that business in partnership or partnerships," a Seven spokesperson told iTNews.