CFTC subpoenas Harris Bank over MF Global: Sources

``Harris Bank, a division of Bank of Montreal, was the main custodian for customer money deposited with MF Global and kept in segregated accounts. The subpoena was served within the past week, according to the people familiar, who were not authorized to discuss the subpoena publicly... The CFTC has been joined in the investigation by the Federal Bureau of Investigation and the U.S. Attorney's Office in Manhattan, which has opened a grand jury investigation into the collapse of MF Global and the missing money.''