BMO Financial Group issued a statement late Tuesday indicating that it has suspended a couple of traders following its large commodity trading losses.

The bank confirmed that two of its commodity trading professionals are on leave pending the results of an external review.

The review comes after the bank surprised investors with the announcement that it expects to record $350 million to $450 million in paper losses this quarter stemming from commodity trades, particularly in natural gas.

BMO is also suspending all of its business relationships with the brokerage firm, Optionable, Inc., as well as all derivatives trading through that firm, pending the results of a full external review, which it describes as ongoing.

In addition, the company said that it has changed the operating structure of BMO Capital Markets, “in order to provide additional oversight of the commodities business, which now reports within a business line most experienced in the trading and valuation of derivatives”.