According to an unnamed source cited in a report in British daily the Times, the bank is believed to be mulling buying a European scheme with a value of around $400 million.
The bank has also identified a number of other targets, and has a fund of around $1 billion to make these acquisitions, the source added.
News of the prospective deal comes just two weeks after Citigroup purchased a shell company containing the Thomson Regional Newspapers fund for around $400 million.
That deal represented the first time that a bank in Britain had bought a company retirement fund.
Since then Citigroup has been inundated with calls from companies looking to offload their final salary pension schemes, according to the newspaper.
Citigroup declined to comment on the report.