Mitsubishi UFJ Financial Group <8306.T>, Mizuho Financial Group <8411.T> and Sumitomo Mitsui Financial Group <8316.T> have submitted bids to buy the Japanese retail brokerage unit of Citigroup Inc in a deal that could raise about 600 billion yen ($6 billion), five people with direct knowledge of the sale said.

Citigroup closed the final bidding for its planned sale of Nikko Cordial Securities on Monday, the sources said, as part of the struggling U.S. bank's global efforts to raise cash.

The sources asked not to be identified because the transaction is not public. A spokesman for Nikko Citi Holdings, the bank's holding company in Japan, declined to comment.

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

Citigroup spent about 1.5 trillion yen to acquire the Nikko Cordial franchise, which has about 110 branches and some 25 trillion yen in client assets as of December, second only to Nomura Holdings Inc <8604.T> among brokers in Japan.

Mitsubishi UFJ, Mizuho and Sumitomo Mitsui -- Japan's three largest banks -- all see buying Nikko Cordial as a potential way to boost their position in the Japanese market.

The U.S. bank, reeling from more than $85 billion of write-downs and credit costs since mid-2007, has divided its assets into Citicorp, which houses the businesses it considers its main operations, and Citi Holdings, which includes units and assets it is looking to shed, including Nikko Cordial and Nikko Asset Management.

Until recently, the bank had viewed Nikko Citigroup as a major unit that it intended to hold on to.

But Citigroup, eager to raise as much cash as possible, added the part of Nikko Citigroup that provides services to small and medium Japanese companies to the Nikko Cordial sale, the sources said.

(Reporting by Taro Fuse; Writing by Junko Fujita; Editing by Hugh Lawson)

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