"Due to the situation in Spanair, SAS has decided to make a write down of the outstanding debt and receivables on Spanair (which will) affect the SAS Group's result as a non-recurring item and equity negatively by 1.7 billion kronor in total," the Scandinavian airline said in a statement.
The company said however that the effect on its "liquid assets" would amount to between 200 and 300 million kronor.
SAS, which sold off most of its once wholly owned subsidiary Spanair in 2009, said it still owned 10.9 percent of the Spanish airline.
But it stressed "the value of these shares has already been written down and are booked at zero value."
SAS said it would be a creditor in Spanair's bankruptcy process, and pointed to the 10.6 billion kronor "financial preparedness" it listed in its third quarter earnings report. The write-down would "have a limited effect on SAS liquidity", it said.
SAS, which posted a slim profit in the third quarter, is scheduled to announce its results for the fourth quarter and full-year 2011 on February 8.
The company said Friday that, not including the write-down and other non-recurring items, it expected the full year result to be positive.