RBS is set to be hit by a new multi-billion-pound charge for mis-selling mortgage-backed securities.
A formal statement confirming the charge could come as soon as today with RBS directors expected to discuss the move in a board meeting this week.
The charge could be between $3bn (£2.4bn) and $4bn, sources told Sky News last night.
The state-owned bank has reportedly set billions of dollars aside to settle a fine with the US Department of Justice (DoJ).
The head of UK Financial Investments (UKFI), which looks after the taxpayer's stake in the bank, told MPs last year that it could be anything up to $12bn.
Last month, the DoJ sued Barclays and two of its executives over alleged fraud issuing mortgage-backed securities during the 2008-2009 financial crisis.