Glencore took a $US7.7 billion write-down in 2013 on the $US29 billion "merger" with Xstrata it executed the same year, with the bulk of that taken on goodwill.
Refer to the input text as context and select the correct relationship between 'Xstrata' and 'Glencore' from the available options.
Options: distributed by, platform, owned by, operator