Correction to Circular

Mendell Helium plc

("Mendell Helium" or the "Company")

Correction to Circular

Mendell Helium announces a minor correction to the circular and notice of general meeting posted to shareholders on 1 May 2026.

Note 10 in the explanatory notes as to the proxy, voting and attendance procedures at the general meeting on page 31 incorrectly stated that the deadline for appointing proxies through CREST was 10.00 a.m. on 1 May 2026. The correct deadline is 10.00 a.m. on 14 May 2026 and the circular and explanatory notes should be read accordingly.

The general meeting will be held at 10.00 a.m. on Monday 18 May 2026, at the Company's offices at Office 12, Arran House, Arran Road, Perth, Perthshire PH1 3DZ.

The Directors of the Company are responsible for the release of this announcement.

ENDS

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Overview of Mendell Helium

Mendell Helium announced on 27 June 2024 that it has entered into an option agreement to acquire the entire issued share capital of M3 Helium through the issue of 57,611,552 new ordinary shares in Mendell Helium to M3 Helium's shareholders. The option has been exercised and completion of the acquisition is expected to take place on 18 May 2026.

M3 Helium's flagship well, Rost 1-26, is in Fort Dodge, just to the east of Dodge City, Kansas. It has been tested as containing 5.1% helium composition and a drill stem test yielded a maximum flow rate of approximately 2,900 Mcf per day. Water removed from Rost 1-26 is delivered to Brobee, a nearby disposal well that has been permitted at 5,000 barrels of water per day at 1,200 psi. Production at Rost 1-26 commenced in early November 2025 and the most recently recorded flow rate in December 2025 was 250 Mcf per day equating to approximately $1.4 million of helium per year (at $300/Mcf helium).

M3 Helium has subsequently drilled a second well, Rost 2-26, which is currently being completed. It also owns additional leases in the Fort Dodge area capable of supporting a further four new production wells. It has also agreed a joint venture with Ritchie Exploration, Inc. to recomplete the Schneweis Ventures 13, a well with a drill stem test of over 10,000 Mcf per day and a historic flow rate of 300 Mcf per day.

At the Rost wells in Fort Dodge, M3 Helium treats the raw gas on site to concentrate the helium and has leased two tube trailers which it uses for deliveries to its offtaker.

M3 Helium also has interests in five producing wells (Peyton, Smith, Nilson, Bearman and Dimmitt) within the Hugoton gas field in South-Western Kansas, one of the largest natural gas fields in North America. Significantly these wells are in the proximity of a gathering network and the Jayhawk gas processing plant meaning that producing wells are all tied into the infrastructure.

M3 Helium is also developing a Bitcoin mining operation in Nebraska where it has taken a lease of land prospective for biogenic methane and has drilled a pilot well (Jasper). It is onboarded for custody with Bitgo Inc. and its Bitcoin treasury management policy is available at https://mendellhelium.com/bitcoin-treasury.

Forward Looking Statements

These forward-looking statements are not historical facts but rather are based on the Company's current expectations, estimates, and projections about its industry; its beliefs; and assumptions. Words such as 'anticipates,' 'expects,' 'intends,' 'plans,' 'believes,' 'seeks,' 'estimates,' and similar expressions are intended to identify forward-looking statements. These statements are not a guarantee of future performance and are subject to known and unknown risks, uncertainties, and other factors, some of which are beyond the Company's control, are difficult to predict, and could cause actual results to differ materially from those expressed or forecasted in the forward-looking statements. The Company cautions security holders and prospective security holders not to place undue reliance on these forward-looking statements, which reflect the view of the Company only as of the date of this announcement. The forward-looking statements made in this announcement relate only to events as of the date on which the statements are made. The Company will not undertake any obligation to release publicly any revisions or updates to these forward-looking statements to reflect events, circumstances, or unanticipated events occurring after the date of this announcement except as required by law or by any appropriate regulatory authority.

Important Notices

Mendell Helium plc (the "Company") intends in the future to invest surplus cash and hold treasury reserves in bitcoin. Bitcoin is a type of cryptocurrency or crypto asset. Whilst the Board of Directors of the Company considers holding bitcoin to be in the best interests of the Company, the Board is aware that the financial regulator in the UK (the "Financial Conduct Authority" or "FCA") considers investment in bitcoin to be high risk. However, the Board of Directors of the Company consider bitcoin to be an appropriate store of value and growth for the Company's reserves and, accordingly, the Company may in the future be materially exposed to bitcoin. Such an approach is innovative, and the Board of Directors of the Company wish to be clear and transparent with prospective and actual investors in the Company on the Company's position in this regard. An investment in the Company is not an investment in bitcoin, either directly or by proxy.

The Company is neither authorised nor regulated by the FCA and cryptocurrencies (such as bitcoin) are unregulated in the UK. As with most other investments, the value of bitcoin can go down as well as up, and therefore the value of bitcoin holdings can fluctuate. The Company may not be able to realise any future bitcoin exposure for the same as it paid in the first place or even for the value the Company ascribes to bitcoin positions due to these market movements. As bitcoin is unregulated, the Company is not protected by the UK's Financial Ombudsman Service or the Financial Services Compensation Scheme. Prospective investors in the Company are encouraged to do their own research before investing.