Exchange operator CME Group said on Tuesday it would require customers to set aside larger sums to back up some swap positions because of uncertainty around the US debt-ceiling debate, according to a notice sent to customers.

CME's clearinghouse plans to increase margin requirements- the deposits that investors must put down to cover their trading positions-for over-the-counter interest-rate swap portfolios by 12% beginning on Wednesday, "due to the additional uncertainty brought by the debt ceiling debate," according to the notice.