J. Christopher Giancarlo, a leading candidate to head the U.S. Commodity Futures Trading Commission under President-elect Donald Trump, called for an overhaul of swaps-trading regulations that he blamed for fracturing global markets.

Giancarlo, currently a Republican member of the CFTC, said in a speech in London Friday that Dodd-Frank Act rules have “caused numerous harms” to the $544 trillion worldwide market by driving trading away from banks and other firms that fall under U.S. oversight. He said overseas traders have shunned deals with financial firms that bear the “scarlet letters” of U.S. rules, contributing to less efficient and more volatile prices in the market.

“The time has come for the CFTC to revisit its flawed swaps trading rules to better align them to market dynamics, allow U.S. swap intermediaries to fairly compete in world markets and reverse the tide of global market fragmentation,” Giancarlo, a former swap-brokerage executive, said at an International Swaps and Derivatives Association conference.