The main lenders of bankrupt German retail giant Arcandor said they may sell the group's stake in Thomas Cook.The banks hold a 43.9% stake in the UK travel firm that was granted to them as collateral.Germany's Bayern LB, Commerzbank and Royal Bank of Scotland are considering their options and said the most likely outcome would involve a market placing, off market sales or some combination of the two. No course of action has been determined at this stage, they added.Arcandor, which owns department-store chain Karstadt and the Quelle catalogue businesses, filed for bankruptcy in June.