Citigroup ( C) could be close to selling its Japanese brokerage unit for as much as $6 billion, according to a report Monday.

Japan's three largest banks -- Mitsubishi UFJ Financial Group ( MTU), Mizuho Financial Group ( MFG) and Sumitomo Mitsui Financial Group -- have all submitted bids for Nikko Cordial, in a deal that could raise about 600 billion yen ($6 billion), according to Reuters, which cited five sources close to the situation.

Citi closed the final bidding for its planned sale of Nikko Cordial Securities on Monday, Reuters said.

The sale includes part of Nikko Citigroup Ltd, the wholesale brokerage unit of Citi, but not Nikko Asset Management, its fund management arm that may be sold off in a separate transaction, Reuters said.

Citi has been looking for ways to cut expenses and add to capital as it shaves non-core businesses from its lineup. The sale of Nikko follows the joint venture the company recently created between Morgan Stanley ( MS) and Smith Barney, Citi's profitable U.S. brokerage force, and the sale of its German retail banking operations.

The company said Friday that it beat quarterly estimates and posted a profit for the first quarter -- its first since mid-2007.

Still Citi shares were falling 15.6% to $3.08 in recent trading on Monday, as Wall Street worried about the company's credit losses going forward.

Bank of America ( BAC) blew past earnings estimates on Monday by posting a profit of $2.8 billion, or 44 cents a share, fueled by one-time gains from its Merrill Lynch acquisition as well as the sale of China Construction Bank shares.