Refer to the input text as context and select the correct relationship between 'Xstrata' and 'Glencore' from the available options.
Options: owner of, operator, currency, owned by

Klein brokered the talks between the bosses of Glencore Plc and Xstrata Plc that led to the $29 billion all-share takeover of the mining group by the commodity trader in 2013.
owned by