KirchMedia, the core rights business of indebted media group Kirch and parent of Germany's biggest commercial broadcaster ProSiebenSat.1, filed for insolvency on Monday. The move ends weeks of fruitless rescue efforts by Rupert Murdoch and Italian Prime Minister Silvio Berlusconi. But the banks ... decided an attempt to avoid insolvency was futile. An insolvency filing by KirchMedia could bring down the whole Kirch empire.