Exercise of Options

25 June 2025

4basebio PLC

("4basebio" or the "Company")

Exercise of Options

Cambridge, UK, 25 June 2025 – 4basebio PLC (AIM: 4BB), an innovation-led provider of novel synthetic DNA products and a non-viral, thermostable nucleic acid delivery platform, announces that, on 19 June 2025, it received notification from two employees of the Company to exercise EMI options over 13,000 ordinary shares (“New Ordinary Shares”) in the Company at an exercise price of £1.18 per share, raising total proceeds of £15,340.

Admission to AIM

Application will be made for the New Ordinary Shares to be admitted to trading on AIM ("Admission"). It is expected that Admission will become effective at 8:00 a.m. on or around 30 June 2025. The New Ordinary Shares will be issued credited as fully paid and will rank in full for all dividends and other distributions declared, made or paid after Admission and will otherwise rank on Admission pari passu in all respects with the existing ordinary shares.

Total Voting Rights

Following Admission, the total number of ordinary shares in issue will be 15,509,393. The Company does not hold any ordinary shares in treasury. Therefore, the total number of ordinary shares with voting rights will be 15,509,393. This figure may be used by shareholders in the Company as the denominator for the calculations by which they will determine if they are required to notify their interest in, or a change to their interest in, the share capital of the Company under the Financial Conduct Authority's Disclosure and Transparency Rules.

This announcement contains inside information for the purposes of Article 7 of EU Regulation 596/2014 as amended by regulation 11 of the market abuse (amendment) (EU Exit) regulations 2019/310.

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Notes to Editors

About 4basebio

4basebio (AIM: 4BB) is an innovation driven life biotechnology company focused on accelerating the development of advanced therapy medicinal products (ATMPs) through its high-performance synthetic DNA products and non-viral, cell targeting nucleic acid delivery platform. The Company’s objective is to become a market leader in the manufacture and supply of high-quality synthetic DNA products for research, therapeutic and pharmacological use as well as development of target specific non-viral vectors for the efficient delivery of payloads in patients.

Forward-looking statements

This announcement may contain certain statements about the future outlook for 4basebio. Although the directors believe their expectations are based on reasonable assumptions, any statements about future outlook may be influenced by factors that could cause actual outcomes and results to be materially different.