Utilize the input text as a context reference, choose the right relationship between 'Glencore' and 'Ivan Glasenberg' from the options.
Options: product/material produced, owned by, chief executive officer, distribution format

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