He argues that investors are not only sending a message to Glencore chief executive Ivan Glasenberg about the need for a less leveraged balance sheet, they are also sending a message to BHP Billiton and Rio Tinto about their unsustainable dividend policies.
Analyze the relationship between 'Glencore' and 'Ivan Glasenberg' within the context of the input sentence.
Options: publisher, member of, stock exchange, owned by