Proposed rules to increase transparency in the $708 trillion private derivatives market may combine for an amplified effect that boosts costs for users, according to industry executives.

Trading in interest-rate, credit-default and other swaps may decrease if several changes are taken together, James Hill, a managing director at Morgan Stanley, said today at the annual conference of the International Swaps and Derivatives Association in Chicago.

“I'm very concerned there's a multiplier effect to this,” Hill said during a panel discussion. “That's something we need to look out for.” He listed increased costs associated with margin for swaps trades, for processing transactions with a clearinghouse and increased capital requirements banks will have to adopt.