Nikko stock fell 16 per cent to 1,000 yen at the close of the market in Tokyo, an 18 month low.
A drop of 28 per cent over two days, the largest two-day slump in at least 22 years, served to wipe $3.1 billion off the firm's market value.
Following an independent investigation, senior managers at the firm have been accused of padding the earnings for 2004.
Since December, five of Nikko's top executives have quit the firm, including its president and chairman.
Hajime Yamamoto, an executive director at its brokerage, Nikko Cordial Securities Inc., announced his resignation on Wednesday.
Mr Yamamoto has taken the blame for the accounting fraud, with the group's in-house committee confirming he played an active role in fabricating figures for the financial year ending March 31st, 2005.
The fraud may cost Nikko its stock market listing, with the Tokyo Stock Exchange announcing yesterday that it will consider the findings of the investigation before making a decision on the firm's future.