Prosecutors served new arrest warrants Oct. 23 to an ex-president and five former executives of Yamaichi Securities Co. and arrested one of its past senior managing directors on suspicion of illegally reimbursing losses on investment incurred by a major leasing company.The action follows complaints filed by the Securities and Exchange Surveillance Commission against Yamaichi and the seven executives earlier during the day with the Tokyo District Public Prosecutor's Office. The firm's head offices were also raided.Compensation for investment losses totaling 316.9 million yen was allegedly made to Showa Leasing Co., prosecutors said. The arrested Yamaichi Securities executives include former President Atsuo Miki, 62, and Hiromichi Ishikawa, 60. Ishikawa resigned Oct. 23 as head of Taiheiyo Securities Co. Profits for the compensation were allegedly earned through trading stock index futures on the Singapore International Monetary Exchange through Yamaichi's own account, sources said. Ishikawa was a senior managing director of Yamaichi at the time the suspected reimbursements were made.