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.
Take context from the input text and decide on the accurate relationship between 'Glencore' and 'Ivan Glasenberg' from the options provided.
Options: distribution format, location of formation, operator, chief executive officer