The Financial Services Agency in Japan has told an investment firm to halt its operations on suspicion that it has lost most of the $US2.3 billion funds it manages.
Operations at AIJ Investment Advisors, which manages group pension funds for more than 100 firms, have been suspended for a month.
The BBC reports the extent and scale of the losses is still being investigated.
FSA head Shozaburo Jimi said the agency would also probe all other investment firms in Japan.
The BBC reports that Olympus, another Japanese company admitted last October that it had hidden losses totalling $US1.7 billion for 20 years.