Currency traders may not be fast enough, at least when itcomes to cleaning up their image.

At issue is a controversial custom called “last look,” whichallows market makers to back out of a trade. After allegations ofabuse, most major banks have recently taken steps to publiclydisclose their trading standards to clients. But not all are onboard. Top 10 dealer BNP Paribas doesn't. And a big player inhigh-frequency trading called Tower Research Capital says itdoesn't need to.

Industry executives — still reeling from paying billionsin currency-rigging fines — concede that the largelyunregulated $5.1 trillion-a-day foreign-exchange market coulduse a dose of transparency. As part of an effort to policethemselves, traders are hoping a global code of conduct that's duein May will help shore up their reputation before regulators crackdown harder.