In an unprecedented move, the parent companies or main banking units of JPMorgan Chase & Co (>> JPMorgan Chase & Co.), Citigroup Inc (>> Citigroup Inc), Royal Bank of Scotland Group Plc (>> Royal Bank of Scotland Group plc), Barclays Plc (>> Barclays PLC) and UBS Group AG (>> UBS Group AG) are likely to plead guilty to rigging foreign exchange rates to benefit their transactions.

The banks are also scrambling to line up exemptions or waivers from the Securities and Exchanges Commission and other federal regulators because criminal pleas trigger consequences such as removing the ability to manage retirement plans or raise capital easily.

In the past, waivers have generally been granted without a hitch. However, the practice has become controversial in the past year, particularly at the SEC, where Democratic Commissioner Kara Stein has criticised the agency for rubber stamping requests and being too soft on repeat offenders.

Negotiating some of the waivers among the SEC's five commissioners could prove challenging because many of these banks have broken criminal or civil laws in the past that triggered the need for waivers.

Many of the banks want an SEC waiver to continue operating as "well-known seasoned issuers" so they can sell stocks and debt efficiently, people familiar with the matter said. Such a designation allows public companies to bypass SEC approval and raise capital "off the shelf" - a process that is speedier and more convenient.

    Several of the people said another waiver being sought by some banks is the ability to retain a safe harbour that shields them from class action lawsuits when they make forward-looking statements.

    The banks involved are also seeking waivers that will allow them to continue operating in the mutual fund business, sources said.

    At least some of the waivers at issue in the forex probe will need to be put to a vote by the SEC's five commissioners. No date has been set yet, a few of the people familiar with the matter said.

The plea deals could be announced as soon as next week, two of the people said, adding that not all the penalties had been finalised yet.

Peter Carr, a spokesman for the U.S. Justice Department, declined comment on the timing or reason for a possible delay of any agreements. Citi, JPMorgan, RBS and UBS did not respond to requests for comment. A Barclays spokesman declined to comment.

The Justice Department has been negotiating with the banks for months over how to resolve allegations that traders colluded to rig rates in the largely unregulated $5.3 trillion (3 trillion pound)-a-day currency market.

If the parent companies of U.S.-based JPMorgan and Citigroup plead guilty as planned, it would be the first time in decades that a major American financial institution has done so.

Last year, when Swiss bank Credit Suisse AG (>> Credit Suisse Group AG) pleaded guilty in the United States to helping wealthy Americans evade taxes, it became the largest institution in over 20 years to admit criminal wrongdoing. It was soon followed by French banking group BNP Paribas SA (>> BNP PARIBAS).

Separately, the Wall Street Journal reported on Thursday night that the U.S. Justice Department voided a 2012 settlement with UBS related to interest-rate rigging.

Citing current and former government officials, it said the negotiations were expected to result in deals next week in which UBS would pay a fine of about $200 million and plead guilty to allegations that its traders manipulated the London interbank offered rate, or Libor, before 2012.

(Reporting by Karen Freifeld, Sarah N. Lynch and Soyoung Kim. Editing by Andre Grenon and Ken Wills)

By Karen Freifeld, Sarah N. Lynch and Soyoung Kim