Nikkei Cites Financial Authority Official
Hacked Customer Accounts Exploited for Price Manipulation
"Stock Prices of at Least 100 Companies Suspected to Have Been Manipulated"
Recently, it was revealed that a hacking crime organization that stole customer accounts from eight Japanese securities firms manipulated the stock prices of at least 100 listed Japanese companies. This means that 2.5% of the approximately 4,000 companies listed on the Japanese stock market have been affected.
On April 28, the Nihon Keizai Shimbun (Nikkei), citing an interview with a financial authority official, reported that hackers are believed to have used the stolen securities customer accounts to manipulate the stock prices of at least 100 listed Japanese companies.
It has been confirmed that the hackers stole customer accounts from eight firms: Rakuten, Nomura, SBI, SMBC Nikko, Monex, Matsui, Daiwa, and Mitsubishi UFJ eSmart Securities. Initially, six companies reported damages to the financial authorities, but during the investigation, the number increased to eight.
Previously, on April 18, Japan's Financial Services Agency (FSA) announced that there had been a total of 1,454 cases of stocks being traded without customer consent at six securities firms over a three-month period starting from February 2025. The total transaction volume reached 95.4 billion yen (approximately 960 billion won). The amount sold was 50.6 billion yen, while the amount purchased was about 44.8 billion yen.
The hacked accounts were exploited to manipulate both domestic and overseas stock prices. Initially, they were used for trading overseas stocks listed on markets such as Hong Kong and Shanghai, but after some companies like Rakuten Securities detected suspicious transactions and blocked certain foreign stock purchase orders by the end of March, the criminal organization reportedly shifted its focus to Japanese listed companies.
The main targets were small and mid-cap stocks. According to the financial authorities, as of the end of March, at least 100 domestic stocks were illegally traded, and repeated manipulation was confirmed even after April. Stocks with low trading volumes and high price volatility, which could be influenced by small orders, were especially targeted.
The funds for price manipulation were reportedly raised by selling stocks already held in existing customer accounts. After purchasing target stocks, the perpetrators would deliberately place high-priced sell orders and then buy those shares through other accounts, using wash trading to inflate the stock prices. This is a classic form of price manipulation, where additional buying follows and causes a sharp price increase.
Nikkei reported that the FSA is monitoring stock price trends and plans to launch a full-scale investigation if the possibility of violating the Financial Instruments and Exchange Act increases. In addition, since the theft of securities accounts is strongly suspected to violate the Act on Prohibition of Unauthorized Computer Access, the police authorities have also begun gathering information.
Meanwhile, the FSA has reportedly urged securities firms to take measures, stating that the damage continues to spread. The agency is recommending the introduction of "multi-factor authentication," which uses several verification methods for logging into stock trading systems or withdrawing funds from accounts. The Japan Securities Dealers Association has also begun considering necessary measures to encourage the wider adoption of multi-factor authentication by securities firms.
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