A wealthy pensioner in a southern Chinese city deciding to lend money to a troubled coal miner in the north about which she knew next to nothing might seem a dangerous gamble.

But Ms Wang did not see it that way – at least not until a few weeks ago. As a VIP customer at a Shenzhen branch of Industrial and Commercial Bank of China, the country’s largest bank by assets, she was offered a special investment product in 2011. For a minimum commitment of Rmb3m ($500,000), she was promised an annual return of 10 per cent for three years. And, she says, the ICBC client manager assured her that the trust product was safe.

“It was my first time buying a trust product. I had never bought any stocks or mutual funds before. Having seen the Lehman Brothers troubles, I was very careful in reviewing the product and I only put my money into it as it didn’t look to be risky,” she told the Financial Times. Like many other investors, she wrongly assumed the trust was “backed by the biggest bank in China”.