To be clear, the non-payment isn’t necessarily an indicator of any problems at the parent company, which is one of China’s largest banks. It’s more likely due to a failure by one of its metals-industry clients to make margin payments to CCBI Global Markets, which is a broker on the LME’s open-outcry trading floor, one of the people said.

That in turn may have left CCBI Global Markets struggling to arrange payment of the unusually large margin calls after the end of the business day in Asia, as nickel prices spiraled higher through the course of Monday in London.

CCB International Holdings didn’t immediately respond to requests for comment. An LME spokesperson declined to comment.

Nickel jumped as much as 90% on Monday, in one of the most dramatic one-day moves ever in commodity markets, touching a record high of $55,000 a ton. Prices have been rallying for weeks, as traders worry about the possibility of disruption to supplies from Russia, the largest exporter of refined nickel.

Monday’s squeeze was driven by market participants with short positions being forced to close them out because they couldn’t meet margin calls, brokers and traders said. Bloomberg has previously reported that Chinese entrepreneur Xiang Guangda — known as “Big Shot” — had a large short position on the LME through his company, Tsingshan Holding Group Co., the world’s largest nickel and stainless steel producer.

Clearinghouses ask brokers to deposit cash, or “margin,” on a daily basis to cover potential losses on their clients’ positions. If the market moves against those positions, the clearinghouse makes a “margin call” to request further funds.