Ownership Filing by Ritchie Garth for Arqit Quantum Inc.

This filing details transactions made by Ritchie Garth, a director at Arqit Quantum Inc., on October 5, 2026. Garth acquired ordinary shares through the conversion of Restricted Share Units (RSUs) in multiple transactions, with the RSUs vesting quarterly. Specifically, 16, 66, 83, and 83 shares were acquired via RSU conversion, increasing the post-transaction holdings to 105,847, 105,913, 105,996, and 106,079 shares, respectively. Additionally, Garth disposed of 127 ordinary shares at a price of $23.7847 per share, resulting in a post-transaction holding of 105,952 shares. The filing also notes that these transactions are exempt from Sections 16(b) and 16(c) of the Act due to the issuer's status as a foreign private issuer. Garth