New York Attorney General Eric Schneiderman's office is investigating the posting of false bids and offers in the foreign exchange options market for emerging market currencies, said a person familiar with the matter on Monday.
The person, who spoke on condition of anonymity, said subpoenas were issued last week to four brokerages: BGC Partners, GFI Group, TFS-ICAP and Tullett Prebon Financial Services.
US authorities have increased their scrutiny of so-called "ghosting" or "spoofing", in which a trader tries to create a false appearance of market interest in a stock, commodity or other asset by placing orders and then immediately canceling them. Authorities say such orders can be manipulative.
Representatives of BGC, ICAP and Tullett Prebon declined to comment. GFI is majority-owned by BGC.
Shares of each of the publicly traded companies were trading lower on Monday, in a broadly flat market.
This month, a jury in Chicago convicted a high-frequency trader of commodities fraud and spoofing in the US government's first criminal prosecution of the trading practice.
The trader, Michael Coscia, was convicted under a relatively new statute that was part of the 2010 Dodd-Frank Wall Street regulatory overhaul, although as a state official Schneiderman operates under different legal authority.
Besides false orders, other tactics in the foreign exchange market have led to billions of dollars in settlements with investors and regulators. US and European regulators have extracted more than $10 billion in settlements with seven banks for failing to stop traders from trying to manipulate foreign exchange rates.
