(Yicai Global) April 22 -- China's regulatory authorities have told the nation’s banks to look into any risks from their oil-related products and submit reports, Yicai Global learned today, after crude oil prices turned negative this week for the first time in history.

Two days ago the May futures contract for West Texas Intermediate, the benchmark for US oil, fell below zero. Some investors who bought Bank of China’s oil-linked products have suffered huge losses.

The bank’s shares [SHA:601988] closed 0.84 percent lower today at CNY3.53 (50 US cents) each.