Your bullion are physically stored and managed by Loomis International at high security bonded storage facilities in Singapore, Hong Kong and Zurich.
Related articles:
What is the fee for storage per year?
Can I visit my bullion and withdraw in person?
Are my bullion holdings fully insured?http://help.stackermarket.com/en/articles/5355742-are-my-bullion-holdings-fully-insured
Is there proof my bullion is physically held in a vault?