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 Chief Executive Ivan Glasenberg is on the record looking to acquire more collieries, solidifying the company's global ranking as the biggest shipper of thermal coal.

Answer: chief_executive_officer