The Securities and Exchange Surveillance Commission on Monday filed a criminal complaint with public prosecutors against a judge seconded to the Financial Services Agency for alleged insider trading.

That same day, the securities market watchdog also filed a complaint against a former employee of the Tokyo Stock Exchange and his father for alleged insider trading.

The commission had launched investigations into both cases earlier this year.

The FSA said the judge, Soichiro Sato, 32, was dismissed Monday. Japan Exchange Group, the TSE's parent organization, also dismissed the employee, Keito Hosomichi, 26, the same day.

According to the commission, Sato was in charge of screening documents for companies planning to launch tender offers at the FSA's Corporate Accounting and Disclosure Division.

From shortly after being assigned to the FSA division in April until around early September, he is believed to have illicitly bought shares in around 10 companies for about ¥9.5 million in his own name, based on undisclosed tender offer information he acquired through his work.

Meanwhile, Hosomichi worked at a TSE division handling listed companies' disclosure of important information.

He is suspected of informing his 58-year-old father of undisclosed tender offer information on three companies obtained through his work, with the intent of helping his father make money. The father allegedly bought ¥17 million in shares illicitly before the information was disclosed to the public.

Both Soichiro Sato and Hosomichi's father are believed to have earned several million yen in profit.

The financial instruments and exchange law prohibits company officials privy to important information, such as on tender offers, from trading shares before disclosure or sharing such information with outside parties.

Share transactions based on undisclosed information obtained during official duties by public servants with authority over the companies are also subject to the regulation.