CME Group Inc., the biggest operator of U.S. futures exchanges, said it will more than double the amount of physical gold it can accept from its clearing members as collateral.

CME Group said in a statement dated Friday that it would increase the amount of bullion its customers can post as collateral to $500 million from $200 million, effective Monday.

The exchange said that the change will allow market participants to better manage their risk and to take advantage of lower gold lease rates.

It gives gold additional credibility as the alternative currency. It might also lessen liquidation of gold, as it is now used as a margin vehicle so participants are not actually liquidating, said Bill O'Neill, partner of commodity investment firm LOGIC Advisors.

Gold is about 15 percent below its record of $1,920.30 an ounce set early September, after a fourth margin increase this year and heavy bouts of liquidation by hedge funds.