Citigroup Inc. on Wednesday confirmed that it will close Banamex USA, a small unit doing business across the U.S.-Mexico border, and agreed to pay $140 million to regulators who said the unit hadn’t done enough to protect itself from money launderers.
Refer to the input text as context and select the correct relationship between 'Banamex' and 'Citigroup' from the available options.
Options: stock exchange, publisher, operator, parent organization