The Competition Commission revealed last week local and international banks were found to have been involved in fixing the rand/dollar exchange rate.
It's seeking an order declaring that the banks responsible should face an administrative penalty equal to 10% of their annual turnover.
The matter has been referred to the Competition Tribunal.
South African institutions including Absa Bank and Investec say they are now looking for answers as to the extent of rand manipulation by traders working for them.
They are joined by international banks including Merrill Lynch International, BNP Paribas, JP Morgan Chase & Co. and a number of others who are also investigating some of their traders.
In all, 18 financial institutions have been implicated.
Investec says it intends to seek further information regarding the charges in order to cooperate further.
But it says the matter is confined to the conduct of a single trader at the institution.
The Sunday Times reported that two Absa Bank traders had also been singled out as being among those responsible for colluding, while conducting rand/dollar trades.
Despite financial institutions arguing that a few traders may be responsible, President Jacob Zuma and National Treasury have warned that the banks implicated should still be punished if found liable.
