The New York Attorney General has opened an investigation into possible manipulation of options contracts tied to currencies of developing nations, according to a person familiar with the matter.

The regulator filed subpoenas last week to four brokers that operate platforms for trading the contracts: Tullett Prebon, BGC Partners, GFI Group and TFS-ICAP, the person said. The investigation was started after the attorney general's office received a tip and is still at a preliminary stage, the person said.