While it’s not clear if any money was lent against the fake documents, it’s a reminder of risks associated with the centuries-old banking mainstay of trade financing. In mid-2014 at Qingdao, metals held in warehouse, mwere believed to have been pledged several times as collateral for loans, leading to hundreds of millions of dollars of bank writedowns.

There isn’t the same concern over London Metal Exchangewarehouse, which use a centralized depository to transfer ownership of metal used in financing deals. When dealing with private warehouses, it’s harder for banks to be sure that the metal is either owned by the borrower or used only once as collateral.

"Issues like this are reflective of the nature of the commodities industry,” said Nikos Nomikos, a professor of shipping risk management at Cass Business School at City University of London. “We may be in the 21st century, but some of the practices in this business go back to the 18th century."The industry has since started looking to technology to make issuing and tracking documents more secure, rather than relying on manually cross-checking records.