Utilize the input text as a context reference, choose the right relationship between Xstrata and Glencore from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

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.

Answer: owned_by