The review of part-nationalized RBS's Global Banking and Markets (GBM) division is likely to be released on Thursday and will see RBS say it may sell some businesses, such as Hoare Govett and cash equities, and scale back across most areas of the unit, the source said.
The source said parts of GBM will be merged with Global Transaction Services (GTS), the payments business that has steady revenues and shares many customers with parts of GBM.
RBS declined to comment.
RBS is 83 percent owned by the government after it had to be bailed out with 46 billion pounds of taxpayer cash during the financial crisis, and Chancellor George Osborne last month said the bank needed to shrink GBM further to become less risky, even after effectively halving in size in the last three years.
Banks have also been told to separate their UK retail banking operations to reduce the risk that taxpayers will need to bail out the industry again, which is likely to make it most costly to fund big investment banking operations such as GBM.
RBS has as a result been conducting a review of GBM, prompting speculation it could shed as many as 10,000 of its 18,900 staff.
Sky News said Thursday's move to cut up to 4,000 jobs could result in a restructuring charge of just over 1 billion pounds.
