Japanese bank Mizuho said it has <A HREF="http://news.zdnet.com/2110-1009_22-5647165.html?tag=zdnn.alert">lost the confidential data of 270,000 account holders.</A> Mizuho Financial Group, which owns the retail bank, said it had lost customer account numbers and names at 167 branches over several years, according to a Financial Times report on Wednesday. The bank is said to have suffered problems integrating systems and managing data since it was formed three years ago.