What is the relationship between Glencore and Ivan Glasenberg in the context of the input sentence. Choose an answer from: 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 [LON:GLEN] chief executive Ivan Glasenberg is backing himself in one of the greatest trades of his life, and Questor is concerned he is backing himself and his investors into a corner.

Answer: chief_executive_officer