Shannon Bell, a Citigroup spokeswoman, said that the company would not comment.

A Citigroup spokeswoman said their departures were unrelated to regulatory matters.

A Citigroup spokeswoman, Leah Johnson, said yesterday that no company official had any more to say about the matter.

A Citigroup spokeswoman said that no final decisions had been made.

A Citigroup spokeswoman referred inquiries back to the exchange.

A Citigroup spokeswoman said the company would not comment until it announced the findings of a broad-based cost review in mid-April.

Leah C. Johnson, a Citigroup spokeswoman, declined to discuss the investigations.

A Citigroup spokeswoman said that the bank, which has asserted that the transaction was proper, had not had time to review the complaint.

A Citigroup spokeswoman said the firm was confident that the original decision of the arbitrators would be upheld.

"We remain utterly committed to a strong control environment," said Christina Pretto, a Citigroup spokeswoman.