Refer to the input text as context and select the correct relationship between 'Glencore' and 'Ivan Glasenberg' from the available options.
Options: chief executive officer, owned by, distribution format, product/material produced

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.
chief executive officer