Tokyo's bourse imposed a record fine of about $2.5 million on Nomura Holdings on Wednesday in the wake of an insider trading scandal at Japan's biggest brokerage.
The Tokyo Stock Exchange (TSE) said it was levying a 200 million yen penalty on the company, and ordering a "business improvement report" detailing what measures had been taken to prevent a repetition.
The Nikkei business daily said the fine reflected the TSE's feeling that Nomura had dented confidence in Japan's capital markets after employees leaked confidential information about future stock offerings.
Small regional exchanges in Osaka and Nagoya were also planning to fine Nomura, the Nikkei said.
In 2010, the TSE slapped a 180 million yen fine on the Japan unit of BNP Paribas Securities in over three fraud cases, the exchange's highest-ever fine before the 200 million yen Nomura penalty reported Wednesday.
The Japan Securities Dealers Association fined Nomura 300 million yen earlier this month over the scandal, which led to the resignation of Nomura chief executive Kenichi Watanabe and chief operating officer Takumi Shibata earlier this year.
In June Nomura released a damning report that warned the firm was overrun with "serious systemic defects that would erode confidence in (Nomura) as a securities company".
The company report said the firm's sales staff tipped off clients about share sales and information often flowed freely between the sales department and Nomura's investment banking and research side, which is usually barred.
Japanese authorities are carrying out a wide-ranging probe into insider trading which, although illegal in Japan, is widespread and carries only token penalties.
The probe comes following renewed pressure to crack down on lax regulations and legal loopholes which have dented the nation's corporate governance image.