Mizuho Securities Faces Insider Trading Probe by Japanese Regulators

Tokyo, Japan – February 16, 2026 – Japan’s Securities and Exchange Surveillance Commission (SESC) is investigating suspected insider trading involving at least one employee of Mizuho Securities Co., Ltd. The investigation has led to a compulsory search of Mizuho Securities’ main office and is ongoing, with the possibility of criminal charges being filed.

Investigation Details

The SESC conducted a compulsory search at Mizuho Securities’ headquarters last month, according to informed sources reported by Jiji Press. The commission is currently analyzing materials seized during the search to determine if a criminal complaint should be submitted to prosecutors. The probe centers on employees within Mizuho Securities’ investment banking division as reported by Bloomberg and as detailed by Archyde. The specific nature of the alleged trading violations has not been publicly disclosed.

Mizuho Securities’ Response

Mizuho Securities released a statement on Monday, February 16, 2026, confirming the investigation and stating its commitment to fully cooperate with the SESC according to Jiji Press. Mizuho Financial Group also confirmed the probe following reports from the Nikkei newspaper as reported by Archyde.

Market Reaction

News of the investigation impacted Mizuho Financial Group’s stock price, which fell 5.3 percent on Monday, marking the steepest single-day decline since April 2025 according to Archyde. This decline occurred alongside broader weakness in banking stocks, influenced by disappointing economic growth data that dampened expectations for potential interest rate hikes by the Bank of Japan.

Recent Insider Trading Cases in Japan

This case is part of a growing trend of insider trading scandals within Japan’s financial industry. Earlier in February 2026, Tokyo prosecutors arrested a former senior executive at Mita Securities over alleged insider trading related to Nidec’s bid for Makino Milling Machine as noted by Archyde. Similar cases emerged across different institutions last year.