Authorities around the world have been investigating a host of rigging scandals including the fixing of Libor, a key financial benchmark used to price trillions of pounds worth of securities, and manipulation of the currency markets.
In May 2015, Barclays, Citigroup, JP Morgan, and Royal Bank of Scotland pleaded guilty in the US to conspiring to rig currencies and agreed to over $2.5bn in fines in total.
The "Cartel" chatroom was at the centre of that case and prosecutors have said the now-infamous online forum was used between 2007 and 2013 to manipulate foreign exchange.
In the banks' sentencing last week, a Connecticut judge called on the authorities to take further action and said: "Frankly I would encourage the government to consider prosecution of individuals".
The DoJ is pushing ahead with the charges against Ashton, Usher and Ramchandani ahead of the inauguration on January 20 of incoming US president Donald Trump, who he is expected to shake-up the department.
The DoJ declined to comment. Lawyers for the men could not be reached.
It comes after former Barclays trader Jason Katz last week pleaded guilty to currency market price-fixing, the first individual to admit wrongdoing in the US criminal probe into foreign exchange.
In July last year, HSBC executive Mark Johnson was dramatically arrested at JFK Airport and, along with another executive who had by then left the bank, was charged over allegations of fraud linked to a $3.5b currency trade in 2011.
Johnson has pleaded not guilty.