Siiibo Securities Co., Ltd. (Headquarters: Chuo-ku, Tokyo; CEO: Kazuki Komura; hereinafter "the Company"), which operates the corporate bond issuance and purchase platform "Siiibo," will introduce passkey authentication for login starting June 30, 2026. In response to the "Comprehensive Guidelines for Supervision of Financial Instruments Business Operators, etc." by the Financial Services Agency and the "Guidelines for Preventing Unauthorized Access, etc. in Internet Transactions" by the Japan Securities Dealers Association, revised on October 15, 2025, securities companies are required to mandate multi-factor authentication that is resistant to phishing. In light of this, our company has introduced "Passkey Authentication" for logging into the Siiibo Securities platform, effective June 30, 2026. As a result, passkey registration is now mandatory for new customers opening accounts with our company. For existing customers, passkey authentication will also become mandatory for login in phases. The introduction of passkey authentication enhances resistance to unauthorized access and phishing attacks from third parties compared to traditional password logins, while also allowing customers to log in smoothly without hassle. ■ Benefits of Passkey Authentication 1) Enhanced Phishing Resistance Passkeys are managed in association with the domain information of the Siiibo Securities site, making them resistant to phishing attacks as authentication will not succeed on fake sites. 2) No Password Entry Required Since the device's authentication method is used as the passkey, even if the password is leaked or the device is lost, third parties cannot log in, preventing unauthorized access. 3) Quick Login Once a passkey is created, login is possible using the device's authentication function, eliminating the need to remember or enter passwords and allowing for a smooth transition to trading. ※ For details, please refer to the Passkey Authentication Guide and FAQ (Portal Page): htt