The retail brokerage, Nikko Cordial Securities, was put up for sale in February, drawing interest from Japan's top three banks, Mitsubishi UFJ Financial Group <8306.T>, Mizuho Financial Group <8411.T> and Sumitomo Mitsui Financial Group <8316.T>. Nikko Cordial has about 110 branches across Japan.
Citigroup may also sell all or part of Nikko Citigroup, its investment banking arm, and Nikko Asset Management, its fund management division, along with the retail brokerage, the sources said.
Citigroup is selling assets after massive losses on toxic securities led to U.S. government bailouts. The bank has taken more than $45 billion of taxpayer money, and the government is expected to become Citigroup's largest investor, with a potential 36 percent stake.
The sources, who were not authorized to speak publicly about the bidding and therefore requested anonymity, said that by selling the units together Citigroup hoped to get the highest price.
Citigroup plans to seek bids for the investment banking operations on April 20, they said.
Japan's Kyodo News, citing banking sources, reported earlier that the three businesses combined could be priced at 800 billion yen ($7.98 billion).
Citigroup spokesman Jon Diat declined to comment on the matter.
Citigroup shares were up 38 cents, or 12.5 percent, at $3.42 on the New York Stock Exchange near midday on Monday.
($1 = 100.238 yen)
(Reporting by Taro Fuse and Emi Emoto, editing by Matthew Lewis nd John Wallace)