Rhodium Resources Pte Ltd., a Singapore-based coal and grains trader, was sued by Malayan Banking Bhd. for failing to make payments to Malaysia’s biggest bank, according to court documents.

Rhodium owes the bank US$3.16 million ($4.3 million) for four bills of exchange drawn by Intra Asia Trading Pte Ltd. as of Sept. 1, the lender said in court filings. Rhodium is a customer of Intra Asia for commodity trading and had agreed to pay the firm for the goods, it said.

A global wave of upheaval among commodities traders has hit banks this year, forcing them to turn to the courts to reclaim loans. The moves have battered the close-knit trading community in Singapore, one of the world’s most important hubs, and exposed the risks to banks that finance the opaque business of moving raw materials around the planet.

The Kuala Lumpur-based bank didn’t accuse Rhodium of any wrongdoing, or provide reasons for the default. Maybank’s representative declined to comment. No one answered an email inquiry to Rhodium.

Intra Asia Trading is a Singapore-based commodities trader. An email inquiry to the company wasn’t returned.

Founded by Srinivas Koneru, Rhodium traded 6.2 million tons of coal and 1.8 million tons of grains and oil seeds in the year ended February 2018, with total turnover of US$2 billion, according to a company brochure.