Add Andy Maack of Vanguard Group Inc. to the list of a dozen or so executives who say that routine misbehavior in the $5.1 trillion-a-day foreign exchange (FX) market persists even after banks paid $10 billion in penalties and a trader was sent to prison.

It's been a year since regulators and industry participants published the FX Global Code, a set of voluntary guidelines aimed at improving standards in the unregulated, over-the-counter market that was rife with misdeeds. While the cleanup effort has helped make the business more transparent, it hasn't done enough to curb the most dubious practices, said Maack, Vanguard's global head of foreign-exchange trading.

“I personally would have a tough time signing that document,” Maack said in an interview. “It needs to go further.”

• See also:
  “Pursuing Best Execution in FX Transactions”

Maack pointed to the controversial, and widely used, practices of last look and front-running as the most objectionable. A dozen industry participants agreed with him. Last look allows dealers to back out of losing trades. Front-running, sometimes called pre-hedging, is a practice in which traders make deals using advance knowledge of clients' private order information. The code allows both under certain circumstances.