THIS ANNOUNCEMENT CONTAINS INSIDE INFORMATION FOR THE PURPOSES OF ARTICLE 7 OF THE MARKET ABUSE REGULATION (EU) 596/2014 (WHICH FORMS PART OF DOMESTIC UK LAW PURSUANT TO THE EUROPEAN UNION (WITHDRAWAL) ACT 2018 ("UK MAR").

NOT FOR RELEASE, PUBLICATION OR DISTRIBUTION, DIRECTLY OR INDIRECTLY, IN WHOLE OR IN PART, IN ANY JURISDICTION WHERE, OR TO ANY OTHER PERSON TO WHOM, TO DO SO MIGHT CONSTITUTE A VIOLATION OR BREACH OF ANY APPLICABLE LAW OR REGULATION. PLEASE SEE THE IMPORTANT NOTICE AT THE END OF THIS ANNOUNCEMENT

THIS ANNOUNCEMENT AMOUNTS TO A FINANCIAL PROMOTION FOR THE PURPOSES OF SECTION 21 OF THE FINANCIAL SERVICES AND MARKETS ACT 2000 ("FSMA") AND HAS BEEN APPROVED BY RETAIL BOOK LIMITED WHICH IS AUTHORISED AND REGULATED BY THE FINANCIAL CONDUCT AUTHORITY (FRN 994238). THIS FINANCIAL PROMOTION IS NOT INTENDED TO BE INVESTMENT ADVICE.

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 QUANTUM BASE HOLDINGS PLC.

NOT FOR RELEASE, PUBLICATION OR DISTRIBUTION IN WHOLE OR IN PART IN OR INTO THE UNITED STATES, CANADA OR JAPAN.

4 December 2025

QUANTUM BASE HOLDINGS PLC

("Quantum Base" the "Company" or the "Group")

Retail Offer by RetailBook

Further to the Company's announcements at 6.17 p.m. and 6.21 p.m. on 2 December 2025 in relation to the Placing and Retail Offer, the Directors now believe that the New Shares to be issued pursuant to the Retail Offer will be eligible for EIS and VCT investments.

In light of this, the Company is extending the duration of the Retail Offer. The Retail Offer is therefore now expected to close at 1 p.m. on 10 December 2025.

Shareholders can claim their EIS certificates by emailing the Company investors@quantumbase.com

All other terms relating to the Retail Offer remain unchanged as announced by the Company at 6.21 p.m. on 2 December 2025.

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 New 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 New Shares if they are in any doubt.

AIM is a market designed primarily for emerging or smaller companies to which a higher investment risk tends to be attached than to larger or more established companies. A prospective investor should be aware of the risks of investing in such companies and should make the decision to invest only after careful consideration and, if appropriate, consultation with an independent financial adviser.

An investment in the Company will place capital at risk. The value of your investment in the Company and any income from it is not guaranteed and can go down as well as rise due to stock market and currency movements. When you sell your investment, you may get back less than the amount originally invested.

Neither past performance nor any forecasts should be considered a reliable indicator of future results.

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.

Enquiries

For more information, please visit https://quantumbase.com/

Important Notices

The contents of this announcement, which has been prepared by and is the sole responsibility of the Company, have been approved by Retail Book Limited ("RetailBook") solely for the purposes of section 21(2)(b) of FSMA.

It is a term of the Retail Offer that the total value of the New Shares available for subscription at the Issue Price under (i) the Retail Offer; and (ii) any other offer to the public in the United Kingdom falling within section 86(4) of FSMA, does not (in aggregate) exceed the equivalent of €8 million. The Retail Offer is offered in the United Kingdom under the exemption from the requirement to publish a prospectus in section 86(1)(e) and 86(4) of FSMA. As such, there is no need for publication of a prospectus pursuant to the Prospectus Regulation Rules of the Financial Conduct Authority, or for approval of the same by the Financial Conduct Authority. The Retail Offer is not being made into any jurisdiction other than the United Kingdom.

Although the Directors believe that the New Shares to be issued pursuant to the Fundraising will be 'eligible shares' and will be capable of being a qualifying holding for the purposes of investment by VCTs and will also satisfy the conditions of section 173 of ITA for the purposes of the EIS and the Directors are not aware of any subsequent change in the qualifying conditions or the Company's circumstances that would prevent the New Shares from being eligible for EIS and VCT investments on this occasion, neither the Directors nor the Company nor RetailBook, nor any of their respective directors, officers, employees, affiliates or advisers give any warranty or undertaking or other assurance that relief will be available in respect of any investment in the New Shares, nor do they warrant or undertake or otherwise give any assurance that the Company will conduct its activities in a way that qualifies for or preserves its status.

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, the Market Abuse Regulation (EU Regulation No. 596/2014) ("MAR") and MAR as it forms part of United Kingdom law by virtue of the European Union (Withdrawal) Act 2018 (as amended).

This announcement is not for publication or distribution in or into the United States.  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 U.S. Securities Act of 1933, as amended (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 New 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. In addition, the Company has not been, and will not be, registered under the US Investment Company Act of 1940, as amended.

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 Australia, Canada, New Zealand, 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.

This announcement does not constitute an offer to sell or issue or a solicitation of an offer to buy or subscribe for New Shares in 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.

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.

RetailBook is a proprietary technology platform owned and operated by Retail Book Limited (registered address at 10 Queen Street Place, London EC4R 1AG). Retail Book Limited is authorised and regulated in the United Kingdom by the Financial Conduct Authority (FRN 994238).

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 Retail Book 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 RetailBook or any of its 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. RetailBook and its 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.

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 New Shares to be issued or sold pursuant to the Retail Offer will not be admitted to trading on any stock exchange other than the London Stock Exchange.

No other documents or materials are incorporated into, or form part of this financial promotion and RetailBook has not carried out any verification or due diligence in respect of any such other documents.

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