German retail giant Arcandor, which owns department-store chain Karstadt and a majority stake in UK holiday firm Thomas Cook, has filed for bankruptcy after the German government rejected calls for state aid.The bankruptcy filing covers Karstadt and its Quelle catalogue businesses, putting around 43,000 jobs in danger. Thomas Cook, in which Arcandor owns 52%, is not affected by the insolvency.Arcandor was seeking €650m of loan guarantees from the government's Economy Fund program but Chancellor Angela Merkel said no aid would be available unless shareholders, creditors and landlords put up more cash themselves.The company said it hopes to keep Karstadt in business and confirmed that it is still in talks with rival Metro, which owns the Kaufhof chain, regarding a potential merger of their department stores.Trading in Arcandor's shares on the Deutsche Börse were suspended.