TOKYO, March 21 (Reuters) - Mizuho Financial Group Inc (8411.T: Quote, Profile, Research), Japan's second-largest bank, will postpone the merger of Mizuho Securities and Shinko Securities Co (8606.T: Quote, Profile, Research) to January 2009, the Nikkei business daily reported on Friday.

The bank expects Mizuho Securities will be hit by further losses related to the U.S. subprime mortgage crisis, making it difficult to set a merger ratio, the newspaper said.

Mizuho had originally planned to merge the brokers in January 2008 but said in November that it would be pushed back to May 2008 due to the uncertain outlook for financial markets brought about by the subprime crisis. (Reporting by Nathan Layne; Editing by Hugh Lawson)