Actress Meryl Streep books a trade during a visit to ICAP, the world's largest interdealer broker, in Jersey City, New Jersey, December 10, 2008.
US authorities have asked for more information about the merger between brokers ICAP and Tullett Prebon.
ICAP said in a statement on Tuesday that it "received a request for additional information and documentary material from the United States Department of Justice in connection with the transaction."
The company seems relatively unfazed by the demand but the company does have a history with the DoJ.
"This request, the details of which are relatively standard in their nature, was expected in the context of the transaction. As such, the Company remains confident that the necessary clearances will be obtained within the timeframe previously announced," ICAP said.
In 2013, ICAP was fined $87 million (£59 million) for its part in the long-running Libor manipulation scandal by the US agency.
In November, it was announced that Tullett Prebon was undertaking a big merger with rival brokerage ICAP to create a "global hybrid voice broking and information business" which will "create the largest player in the industry," the company said.
ICAP said the deal was "proceeding as expected and it is anticipated that completion will take place during 2016."