Olympus shares plunged for a second day as uncertainty loomed over the camera maker's future.
Shares fell 20% in Tokyo on Wednesday, after shedding 30% in the previous session.
On Tuesday, Olympus launched an inquiry after admitting it had hidden losses on its securities investments for decades.
Allegations against Olympus were first made by a Japanese financial publication and the company's former chief executive, Michael Woodford.
Mr Woodford claims he was fired for questioning payments made to financial advisers for their work during a number of acquisitions.
Olympus shares have lost more than three-quarters of their value, or $6bn (£3.7bn), since 14 October, the day Mr Woodford was fired.
On Wednesday, Olympus shares fell by their daily trading limit of 150 yen.
Olympus President Shuichi Takayama, speaking at a news conference on Tuesday, refused to comment on the amount of losses, citing the fact that an external panel was still investigating the issue.
However, the Nikkei news agency reported on Wednesday that losses on the firm's securities investments may have once exceeded $1bn.
When contacted by the BBC, the company refused to confirm or deny the figure quoted by the Nikkei news agency.