Chinese investors piling into a record-breaking rally in precious metals are becoming increasingly exposed to risk, as speculative demand pushes local prices well above international benchmarks. Authorities in the southern city of Shenzhen set up a special task force to oversee the operations of a gold-trading platform, according to a statement from the Luohu district government, after investors faced difficulties withdrawing funds from their accounts. China’s only pure-play silver fund, meanwhile, halted ...