Given the input sentence, please extract the subject and object containing a certain relation in the sentence according to the following relation types, in the format of "relation1: word1, word2; relation2: word3, word4". Relations include: 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.

On September 9, 2015, Twenty-First Century Fox, Inc. (the "Company") and The National Geographic Society (the "Society") issued a joint press release announcing that they have reached an agreement to expand their partnership through which they have owned and operated the properties in National Geographic Channels, a joint venture of domestic and international cable television channels.

Answer: owner_of: National Geographic Society, National Geographic