THIS ANNOUNCEMENT AND THE INFORMATION CONTAINED HEREIN IS RESTRICTED AND NOT FOR RELEASE, PUBLICATION OR DISTRIBUTION, IN WHOLE OR IN PART, IN OR INTO THE UNITED STATES OF AMERICA, CANADA, AUSTRALIA, JAPAN, THE REPUBLIC OF SOUTH AFRICA OR ANY OTHER JURISDICTION IN WHICH SUCH RELEASE, PUBLICATION OR DISTRIBUTION WOULD BE UNLAWFUL. PLEASE SEE THE IMPORTANT NOTICE AT THE END OF THIS ANNOUNCEMENT.

THE COMMUNICATION OF THIS ANNOUNCEMENT AND ANY OTHER DOCUMENTS OR MATERIALS RELATING TO THE RETAIL OFFER AS A FINANCIAL PROMOTION IS ONLY BEING MADE TO, AND MAY ONLY BE ACTED UPON BY, THOSE PERSONS IN THE UNITED KINGDOM FALLING WITHIN ARTICLE 43 OF THE FINANCIAL SERVICES AND MARKETS ACT 2000 (FINANCIAL PROMOTION) ORDER 2005, AS AMENDED (WHICH INCLUDES AN EXISTING MEMBER OF APTAMER GROUP PLC). ANY INVESTMENT OR INVESTMENT ACTIVITY TO WHICH THIS ANNOUNCEMENT RELATES IS AVAILABLE ONLY TO SUCH PERSONS AND WILL BE ENGAGED IN ONLY WITH SUCH PERSONS. THIS ANNOUNCEMENT IS FOR INFORMATIONAL PURPOSES ONLY, AND DOES NOT CONSTITUTE OR FORM PART OF ANY OFFER OR INVITATION TO SELL OR ISSUE, OR ANY SOLICITATION OF AN OFFER TO PURCHASE OR SUBSCRIBE FOR, ANY SECURITIES OF APTAMER GROUP PLC.

THIS ANNOUNCEMENT CONTAINS INSIDE INFORMATION FOR THE PURPOSES OF THE MARKET ABUSE REGULATION (EU) 596 / 2014 WHICH FORMS PART OF UK LAW BY VIRTUE OF THE EUROPEAN UNION (WITHDRAWAL) ACT 2018 ("UK MAR"). UPON THE PUBLICATION OF THIS ANNOUNCEMENT, THIS INSIDE INFORMATION IS NOW CONSIDERED TO BE IN THE PUBLIC DOMAIN AND SUCH PERSONS SHALL THEREFORE CEASE TO BE IN POSSESSION OF INSIDE INFORMATION.

26 March 2026

Aptamer Group plc

("Aptamer", the "Company" or the "Group")

Retail Offer to raise up to £0.5 million

Aptamer Group plc (AIM: APTA), the leading developer of next-generation synthetic binders delivering innovation to the life science industry, announces a retail offer via the BookBuild Platform to raise up to £0.5 million (the "Retail Offer") through the issue of new ordinary shares of 0.1 pence each in the capital of the Company ("Ordinary Shares").

Under the Retail Offer up to 83,333,333 new Ordinary Shares (the "Retail Offer Shares") will be made available at an issue price of 0.6 pence per new Ordinary Share (the "Issue Price") to existing shareholders of the Company in the United Kingdom through financial intermediaries registered with BookBuild.

Participants in the Retail Offer will receive one Warrant to subscribe for new Ordinary Shares for every three new Ordinary Shares subscribed for in the Retail Offer with an exercise price of 0.9 pence per share (being a 50% premium to the Issue Price) at any time in the two years following the date of grant. Warrants will be issued following the General Meeting and settlement of all shares to be issued in connection with the Fundraise.  Warrants will be issued in either CREST or certificated form and will be transferable. No fractions of Warrants will be issued.  The Warrants will not be listed on AIM or any other exchange. The Warrants are conditional on the Resolutions being passed at the General Meeting, as detailed below.

Subject to demand, the Company and Turner Pope may decide to increase the size of the Retail Offer.

In addition to the Retail Offer and as announced earlier today, the Company has conditionally raised gross proceeds of approximately £4.275 million through a placing and subscription of new Ordinary Shares (respectively, the "Placing Shares" and the "Subscription Shares", and together with the Retail Offer Shares, the "New Ordinary Shares") at the Issue Price (respectively, the "Placing" and the "Subscription", and together with the Retail Offer, the "Fundraise"). The first tranche of the Placing of approximately £1.38 million is expected to complete on or around 31 March 2026. Subject to the passing of the Resolutions at the General Meeting, as detailed below, the second tranche of the Placing along with the Subscription of, in aggregate, approximately £2.89 million is expected to complete on or around 16 April 2026.

Net proceeds from the Retail Offer will be used for the same purposes as funds raised from the Placing and the Subscription as set out in the announcement of 25 March 2026.

For the avoidance of doubt, the Retail Offer is not part of the Placing or the Subscription.

The issue of the Retail Offer Shares is conditional upon, inter alia, the passing of the Resolutions to be proposed at the General Meeting, which is expected to be held at the Company's offices at Windmill House, Innovation Way, York YO10 5BR at 11.00 a.m. on 13 April 2026. Conditional upon the passing of the Resolutions, admission of the Retail Offer Shares to trading on the AIM market operated by the London Stock Exchange ("Retail Admission") is expected to occur at 8.00 a.m. on or around 16 April 2026 (or such later time and/or date as the Bookrunners and the Company may agree (being in any event no later than 8.00 a.m. on 30 April 2026)).

Completion of the Retail Offer is conditional, inter alia, upon the completion of the Placing and the Subscription. However, completion of the Placing and the Subscription is not conditional on the completion of the Retail Offer.

Notice for EIS investors

The Company has received a written opinion that, following the proposed changes to the EIS and VCT legislation announced in the Government's Autumn Statement passing into law, the Conditional Placing, Subscription Shares and Retail Offer Shares would qualify for EIS investment. Notwithstanding the Company receiving this opinion, any investor seeking to register their holdings under either scheme is advised to seek their own advice before doing so. Tax reliefs depend on individual circumstances and the Company maintaining its opined qualifying status. Tax rules are subject to change, and if the Company loses its opined qualifying status, tax relief may be withdrawn or need to be repaid.  If investors wish to seek relief under EIS, they should indicate their interest through their chosen Intermediary as part of their participation in the Retail Offer (where such facility is available) and by also emailing the Company at: [email protected].

Expected Timetable in relation to the Retail Offer

Any changes to the expected timetable set out above will be notified by the Company through a Regulatory Information Service. References to times are to London times unless otherwise stated.

Dealing Codes

Retail Offer

The Company values its retail shareholder base and believes that it is appropriate to provide its existing retail shareholders in the United Kingdom the opportunity to participate in the Retail Offer.

The Company is therefore making the Retail Offer available in the United Kingdom only through the financial intermediaries which will be listed, subject to certain access restrictions, on the following website: https://www.bookbuild.live/deals/VQX4MQ/authorised-intermediaries.

Turner Pope Investments (TPI) Ltd ("Turner Pope") will be acting as coordinator in relation to the Retail Offer (the "Retail Offer Coordinator").

Existing retail shareholders can contact their broker or wealth manager ("Intermediary") to participate in the Retail Offer. In order to participate in the Retail Offer, each intermediary must be on-boarded onto the BookBuild Platform and agree to the final terms and the retail offer terms and conditions, which regulate, inter alia, the conduct of the Retail Offer on market standard terms and provide for the payment of commission to any intermediary that elects to receive a commission and/or fee (to the extent permitted by the FCA Handbook Rules) from the Retail Offer Coordinator (on behalf of the Company).

Participation of any intermediary in the Retail Offer is at the absolute discretion of the Retail Offer Coordinator.

Any expenses incurred by any intermediary are for its own account. Eligible Shareholders (as defined below) should confirm separately with any intermediary whether there are any commissions, fees or expenses that will be applied by such intermediary in connection with any application made through that intermediary pursuant to the Retail Offer.

The Retail Offer will be open to Eligible Shareholders in the United Kingdom at 7:05 a.m. on 26 March 2026. The Retail Offer is expected to close at 12:00 p.m. on 30 March 2026, but may, at the absolute discretion of the Retail Offer Coordinator, be closed early or cancelled. Eligible Shareholders should note that financial intermediaries may have earlier closing times. The Retail Offer may close early if it is oversubscribed or otherwise at the absolute discretion of the Retail Offer Coordinator or BookBuild.

If any intermediary has any questions about how to participate in the Retail Offer on behalf of Eligible Shareholders, please contact BookBuild at [email protected].

The Retail Offer is and will, at all times, only be made to, directed at and may only be acted upon by those persons who are, shareholders in the Company.  To be eligible to participate in the Retail Offer (an "Eligible Shareholder"), applicants must meet the following criteria before they can submit an order for Retail Offer Shares: (i) be a current customer of one of the participating intermediaries listed on the above website; (ii) be resident in the United Kingdom; and (iii) be a shareholder in the Company (which may include individuals aged 18 years or over, companies and other bodies corporate, partnerships, trusts, associations and other unincorporated organisations and includes persons who hold their shares in the Company directly or indirectly through a participating intermediary). For the avoidance of doubt, persons who only hold CFDs, spreadbets and/or similar derivative instruments in relation to shares in the Company are not eligible to participate in the Retail Offer.

The Company and the Retail Offer Coordinator reserve the right to scale back any order at their absolute discretion. The Company and the Retail Offer Coordinator reserve the right at their absolute discretion to reject any application for subscription under the Retail Offer without giving any reason for such rejection.

It is vital to note that once an application for Retail Offer Shares has been made and accepted via an intermediary, it cannot be withdrawn.

The Retail Offer Shares will, when issued, be credited as fully paid and will rank pari passu in all respects with existing Ordinary Shares including the right to receive all dividends and other distributions declared, made or paid after their date of issue.

The Retail Offer is offered in the United Kingdom under an exemption from the prohibition of public offers specified in Part 1 of Schedule 1 of the Public Offers and Admissions to Trading Regulations 2024.

The Retail Offer is not being made into any jurisdiction other than the United Kingdom and is not being made to US Persons (as defined in Regulation S of the US Securities Act 1933, as amended).

No offering document, prospectus or admission document has been or will be prepared or submitted to be approved by the Financial Conduct Authority, (or any other authority) in relation to the Retail Offer, and investors' commitments will be made solely on the basis of the information contained in this announcement and information that has been published by or on behalf of the Company prior to the date of this announcement by notification to a Regulatory Information Service in accordance with the Financial Conduct Authority's Disclosure Guidance and Transparency Rules and the Market Abuse Regulation (EU Regulation No. 596/2014) ("MAR") as it forms part of United Kingdom law by virtue of the European Union (Withdrawal) Act 2018 (as amended).

There is a minimum subscription of £100 per investor under the terms of the Retail Offer which is open to Eligible Shareholders in the United Kingdom subscribing via the intermediaries which will be listed, subject to certain access restrictions, on the following website: https://www.bookbuild.live/deals/VQX4MQ/authorised-intermediaries

There is no maximum application amount to apply in the Retail Offer except that the aggregate total consideration for the Retail Offer shall not exceed £500,000.00. The terms and conditions on which investors subscribe will be provided by the relevant financial intermediaries including relevant commission or fee charges.

Investors should make their own investigations into the merits of an investment in the Company. Nothing in this announcement amounts to a recommendation to invest in the Company or amounts to investment, taxation or legal advice.

It should be noted that a subscription for Retail Offer Shares and investment in the Company carries a number of risks. Investors should take independent advice from a person experienced in advising on investment in securities such as the Retail Offer Shares if they are in any doubt.

Unless otherwise defined, definitions contained in this Announcement have the same meaning as set out in the announcement made by the Company on 25 March 2026.

This Announcement is made in accordance with the Company's obligations under Article 17 of UK MAR and the person responsible for arranging for the release of this Announcement on behalf of Aptamer is Andrew Rapson, Chief Financial Officer.   

For further information please contact:

About Aptamer Group

Aptamer Group is a leading developer of next-generation synthetic binders delivering innovation to the life sciences industry. The Group develops Optimer® binders, advanced molecules that work like antibodies by attaching to specific targets in the body. These binders are used in medicine, diagnostic tests, and research tools, offering benefits like high stability, reliable performance, and lower costs compared to traditional antibodies.

Aptamer operates a fee-for-service business in the US$210 billion market for antibody alternatives, working with all top 10 global pharmaceutical companies. It is also building valuable Optimer® assets with partners, aiming for future licensing revenue.

Founded in 2008, the Group listed on the London Stock Exchange AIM market in December 2021 and is headquartered in York, UK.

To register for news alerts by email go to https://aptamergroup.com/investors/investor-news-email-alerts/

This announcement should be read in its entirety. In particular, the information in the "Important Notices" section of the announcement should be read and understood.

IMPORTANT NOTICES

The content of this announcement, which has been prepared by and is the sole responsibility of the Company.

The Retail Offer is only open to investors in the United Kingdom who fall within Article 43 of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005, as amended (which includes an existing member of the Company).

This announcement and the information contained herein is not for release, publication or distribution, directly or indirectly, in whole or in part, in or into or from the United States (including its territories and possessions, any state of the United States and the District of Columbia (the "United States" or "US")), Australia, Canada, Japan, the Republic of South Africa, any member state of the EEA or any other jurisdiction where to do so might constitute a violation of the relevant laws or regulations of such jurisdiction.

The Retail Offer Shares have not been and will not be registered under the US Securities Act of 1933, as amended (the "US Securities Act") or under the applicable state securities laws of the United States and may not be offered or sold directly or indirectly in or into the United States. No public offering of the Retail Offer Shares is being made in the United States. The Retail Offer Shares are being offered and sold outside the United States in "offshore transactions", as defined in, and in compliance with, Regulation S under the US Securities Act ("Regulation S") to non-US persons (within the meaning of Regulation S). In addition, the Company has not been, and will not be, registered under the US Investment Company Act of 1940, as amended.

This announcement does not constitute an offer to sell or issue or a solicitation of an offer to buy or subscribe for Retail Offer Shares in the United States, Australia, Canada, New Zealand, Japan, the Republic of South Africa, any member state of the EEA or any other jurisdiction in which such offer or solicitation is or may be unlawful. No public offer of the securities referred to herein is being made in any such jurisdiction.

This announcement is not for publication or distribution, directly or indirectly, in or into the United States of America.  This announcement is not an offer of securities for sale into the United States.  The securities referred to herein have not been and will not be registered under the US Securities Act and may not be offered or sold in the United States, except pursuant to an applicable exemption from registration.  No public offering of securities is being made in the United States.

The distribution of this announcement may be restricted by law in certain jurisdictions and persons into whose possession any document or other information referred to herein comes should inform themselves about and observe any such restriction. Any failure to comply with these restrictions may constitute a violation of the securities laws of any such jurisdiction.

Each of Turner Pope ("Broker") and SPARK Advisory Partners Limited ("SPARK" or "Nominated Adviser") (together, the "Banks") is authorised and regulated in the United Kingdom by the Financial Conduct Authority, is acting exclusively for the Company and for no-one else and will not regard any other person (whether or not a recipient of this announcement) as its client in relation to the Retail Offer and will not be responsible to anyone other than the Company for providing the protections afforded to its clients, nor for providing advice in connection with the Retail Offer, Admission and the other arrangements referred to in this announcement.

The value of Ordinary Shares and the income from them is not guaranteed and can fall as well as rise due to stock market movements. When you sell your investment, you may get back less than you originally invested. Figures refer to past performance and past performance is not a reliable indicator of future results. Returns may increase or decrease as a result of currency fluctuations.

Certain statements in this announcement are forward-looking statements which are based on the Company's expectations, intentions and projections regarding its future performance, anticipated events or trends and other matters that are not historical facts. These forward-looking statements, which may use words such as "aim", "anticipate", "believe", "intend", "estimate", "expect" and words of similar meaning, include all matters that are not historical facts. These forward-looking statements involve risks, assumptions and uncertainties that could cause the actual results of operations, financial condition, liquidity and dividend policy and the development of the industries in which the Company's businesses operate to differ materially from the impression created by the forward-looking statements. These statements are not guarantees of future performance and are subject to known and unknown risks, uncertainties and other factors that could cause actual results to differ materially from those expressed or implied by such forward-looking statements. Given those risks and uncertainties, prospective investors are cautioned not to place undue reliance on forward-looking statements.

These forward-looking statements speak only as at the date of this announcement and cannot be relied upon as a guide to future performance. The Company and Turner Pope and SPARK expressly disclaim any obligation or undertaking to update or revise any forward-looking statements contained herein to reflect actual results or any change in the assumptions, conditions or circumstances on which any such statements are based unless required to do so by the Financial Conduct Authority, the London Stock Exchange or applicable law.

The information in this announcement is for background purposes only and does not purport to be full or complete. None of Turner Pope or SPARK or any of their affiliates, accepts any responsibility or liability whatsoever for, or makes any representation or warranty, express or implied, as to this announcement, including the truth, accuracy or completeness of the information in this announcement (or whether any information has been omitted from the announcement) or any other information relating to the Company or associated companies, whether written, oral or in a visual or electronic form, and howsoever transmitted or made available or for any loss howsoever arising from any use of the announcement or its contents or otherwise arising in connection therewith. The Banks, BookBuild and their affiliates, accordingly, disclaim all and any liability whether arising in tort, contract or otherwise which they might otherwise be found to have in respect of this announcement or its contents or otherwise arising in connection therewith.

Any indication in this announcement of the price at which the Ordinary Share have been bought or sold in the past cannot be relied upon as a guide to future performance. Persons needing advice should consult an independent financial adviser. No statement in this announcement is intended to be a profit forecast and no statement in this announcement should be interpreted to mean that earnings or target dividend per share of the Company for the current or future financial years would necessarily match or exceed the historical published earnings or dividends per share of the Company.

Neither the content of the Company's website (or any other website) nor the content of any website accessible from hyperlinks on the Company's website (or any other website) is incorporated into or forms part of this announcement. The Retail Offer Shares to be issued or sold pursuant to the Retail Offer will not be admitted to trading on any stock exchange other than the AIM Market of the London Stock Exchange plc.

It is further noted that the Retail Offer is only open to, and this announcement is directed solely at, investors in the United Kingdom who fall within Article 43 of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005, as amended (which includes an existing member of the Company). Accordingly, this announcement does not require the approval of the relevant communication by an authorised person.

SPARK, which is authorised and regulated by the FCA in the United Kingdom, is acting as Nominated Adviser to the Company in connection with the Fundraise. SPARK will not be responsible to any person other than the Company for providing the protections afforded to clients of SPARK or for providing advice to any other person in connection with the Fundraise or any acquisition of shares in the Company. SPARK has not authorised the contents of, or any part of, this announcement, no representation or warranty, express or implied, is made by SPARK in respect of such contents, and no liability whatsoever is accepted by SPARK for the accuracy of any information or opinions contained in this Announcement or for the omission of any material information, save that nothing shall limit the liability of SPARK for its own fraud. SPARK's responsibilities as the Company's nominated adviser under the AIM Rules for Nominated Advisers are owed solely to the London Stock Exchange and are not owed to the Company or to any Director or to any other person.

Turner Pope, which is authorised and regulated by the FCA in the United Kingdom, is acting as sole broker and bookrunner to the Company in connection with the Fundraise. Turner Pope will not be responsible to any person other than the Company for providing the protections afforded to clients of Turner Pope or for providing advice to any other person in connection with the Fundraise or any acquisition of shares in the Company. Turner Pope is not making any representation or warranty, express or implied, as to the contents of this Announcement. Turner Pope has not authorised the contents of, or any part of, this Announcement, and no liability whatsoever is accepted by Turner Pope for the accuracy of any information, or opinions contained in this Announcement or for the omission of any material information, save that nothing shall limit the liability of Turner Pope for its own fraud.

UK Product Governance Requirements

Solely for the purposes of the product governance requirements of Chapter 3 of the FCA Handbook Product Intervention and Product Governance Sourcebook (the "UK MiFIR Product Governance Requirements"), and disclaiming all and any liability, whether arising in tort, contract or otherwise, which any "manufacturer" (for the purposes of the UK MiFIR Product Governance Requirements) may otherwise have with respect thereto, the Retail Offer Shares have been subject to a product approval process, which has determined that the Retail Offer Shares are: (i) compatible with an end target market of retail investors and investors who meet the criteria of professional clients and eligible counterparties, each as defined in paragraphs 3.5 and 3.6 of COBS; and (ii) eligible for distribution through all permitted distribution channels (the "Target Market Assessment"). Notwithstanding the Target Market Assessment, distributors should note that: the price of the Retail Offer Shares may decline and investors could lose all or part of their investment; the Retail Offer Shares offer no guaranteed income and no capital protection; and an investment in the Retail Offer Shares is compatible only with investors who do not need a guaranteed income or capital protection, who (either alone or in conjunction with an appropriate financial or other adviser) are capable of evaluating the merits and risks of such an investment and who have sufficient resources to be able to bear any losses that may result therefrom. The Target Market Assessment is without prejudice to any contractual, legal or regulatory selling restrictions in relation to the Retail Offer.

For the avoidance of doubt, the Target Market Assessment does not constitute: (a) an assessment of suitability or appropriateness for the purposes of Chapters 9A or 10A respectively of COBS; or (b) a recommendation to any investor or group of investors to invest in, or purchase, or take any other action whatsoever with respect to the Retail Offer Shares. Each distributor is responsible for undertaking its own target market assessment in respect of the Retail Offer Shares and determining appropriate distribution channels.

EU Product Governance Requirements

Solely for the purposes of the product governance requirements contained within: (a) EU Directive 2014/65/EU on markets in financial instruments, as amended ("MiFID II"); (b) Articles 9 and 10 of Commission Delegated Directive (EU) 2017/593 supplementing MiFID II; and (c) local implementing measures (together, the "MiFID II Product Governance Requirements"), and disclaiming all and any liability, whether arising in tort, contract or otherwise, which any "manufacturer" (for the purposes of the MiFID II Product Governance Requirements) may otherwise have with respect thereto, the Retail Offer Shares have been subject to a product approval process, which has determined that the Retail Offer Shares are: (i) compatible with an end target market of retail investors and investors who meet the criteria of professional clients and eligible counterparties, each as defined in MiFID II; and (ii) eligible for distribution through all distribution channels as are permitted by MiFID II (the "EU Target Market Assessment"). Notwithstanding the EU Target Market Assessment, distributors should note that: the price of the Retail Offer Shares may decline and investors could lose all or part of their investment; the Retail Offer Shares offer no guaranteed income and no capital protection; and an investment in the Retail Offer Shares is compatible only with investors who do not need a guaranteed income or capital protection, who (either alone or in conjunction with an appropriate financial or other adviser) are capable of evaluating the merits and risks of such an investment and who have sufficient resources to be able to bear any losses that may result therefrom. The EU Target Market Assessment is without prejudice to the requirements of any contractual, legal or regulatory selling restrictions in relation to the Retail Offer.

For the avoidance of doubt, the EU Target Market Assessment does not constitute: (a) an assessment of suitability or appropriateness for the purposes of MiFID II; or (b) a recommendation to any investor or group of investors to invest in, or purchase or take any other action whatsoever with respect to the Retail Offer Shares. Each distributor is responsible for undertaking its own target market assessment in respect of the Retail Offer Shares and determining appropriate distribution channels.