On the heels of an earlier development today that Citigroup (NYSE:C) was nearing a guilty plea to FX manipulation charges, the number has swelled to upwards of five major banks, according to a Reuters report.

The US Department of Justice (DOJ) investigation has included the five major banks, Citigroup, JPMorgan, Royal Bank of Scotland (RBS), UBS AG, and Barclays Plc, which collectively alleged allegations of FX rate manipulation. The latest development indecently targets the parent banking groups, rather than respective subsidiaries, the first such instance in decades.

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The potential US DOJ settlement with parent groups represents a departure from the usual scenario, which typically targets smaller foreign subsidiaries to allay the layoffs of innocent employees. Perhaps more importantly, the repercussions of guilty pleas also could result in the renegotiation of respective regulatory exemptions in order to prevent any stymied business.

A similar situation transpired last month, when Deutsche Bank AG and Barclays Plc were facing the tangible prospect of holdups for their FX settlements, given an ongoing evaluation by the New York State (NYS) Department of Financial Services over currency manipulation.

The guilty pleas with the US DOJ made by each bank will in all probability result in antitrust charges via collusion by traders in an attempt to rig foreign currency rates. A guilty would also bring a hefty fine, with banks expected to fork over penalties of upwards of $1 billion or more, with the aggregate total of the five banks possibly overtaking the $4.3 billion in fines paid by a six banks to global regulators last November.