One of the instant message groups of senior traders from Barclays Plc, Citigroup and Royal Bank of Scotland Group Plc is now under review by regulatory authorities. The review involves the possible participation of bank executives in potential manipulation of the foreign exchange market. This was confirmed by four people with intimate knowledge of the ongoing investigations.

The coverage of the investigation is the last three years and would go into the exchange of messages between dealers. The terminals used Bloomberg terminals to outline details of their positions as well as client orders. There would also be reviews of made trades before setting of key benchmarks according to two sources. The sources sought not to be identified because the investigation would be ongoing.

Other firms included in the investigation such as UBS AG when these individual traders moved from one employer to another. According to some groups, the said message group had earned the monicker 'The Cartel'. 

According to two sources, regulators are reviewing if there were messages attempting to manipulate the market. The four identified banks manage for more than 40% of trading for the total USD5.3 trillion a day forex market, according to a survey conducted by Euromoney Institutional Investor Plc.