Ad hoc announcement pursuant to Art. 53 LR

Leclanché announces filing of request to extend the publication deadline for the 2025 Annual Report and the temporary suspension of trading of its registered shares on SIX Swiss Exchange as of 1June 2026

• Leclanché will be unable to publish its 2025 annual report by 31^st May 2026, the initial extended deadline granted by SIX Exchange Regulation AG (SER) on 30^th April 2026.
• Leclanché has filed on time a request to extend the deadline for publishing its 2025 annual report until 31^st July 2026 but has not yet received the decision by the SER’s Issuers Committee.
• Consequently, the trading of the Leclanché registered shares on SIX Swiss Exchange will be temporary suspended as of 1st June 2026 according to art. 57 of the SIX listing rules and as stated in the decision of SER concerning the temporary exemption from the disclosure obligation in connection with the publication and the filing of the 2025 annual report dated 30^th April 2026.
• To support its going concern assessment through June 2027, the Company is in advanced discussions with a strategic partner regarding a financing arrangement that is expected to facilitate the publication of its 2025 annual report.

YVERDON-LES-BAINS, Switzerland, 1^st June, 2026 – Leclanché SA (SIX: LECN), one of the world's leading energy storage companies, announces that it will be unable to publish its 2025 annual report by 31^st May 2026, the initial extended deadline granted by SIX Exchange Regulation AG (SER) on 30^th April 2026.

Leclanché has submitted a timely second request to the SER for an extension of the deadline to publish its 2025 annual report until 31^st July 2026. However, the decision from the SER’s Issuers Committee is still pending.

As a result, the trading of the Leclanché registered shares on SIX Swiss Exchange will be temporary suspended as of 1^st June 2026 according to art. 57 of the SIX listing rules and as stated in the decision of SER concerning the temporary exemption from the disclosure obligation in connection with the publication and the filing of the annual report 2025 dated 30^th April 2026.

As previously disclosed, the Company continues to implement a series of measures to maintain a positive equity position and demonstrate its ability to operate as a going concern through at least June 2027.

The principal measures implemented and currently under execution include:

• The Company previously announced on the 27^th April, 2026 that it made use of its rights under a conversion facilitation agreement to request that the majority shareholder mandatorily converts debt in the amount of approximately CHF 10 million into equity.
• Financing: The Company is in advanced negotiations regarding a framework agreement with a new strategic partner that is expected to provide additional funding and support the Company's ongoing efforts to reinforce its going concern assessment through June 2027.

The combination of these actions aims to strengthen the Company’s balance sheet and ensure long-term sustainability.

Given the ongoing implementation of these initiatives, Leclanché will not be able to publish its 2025 annual report by 31^st May 2026 and remains confident that it will be able to publish its 2025 annual report within the next few days.

For more information, write to info@leclanche.com or visit www.leclanche.com.

# # #

About Leclanché

Leclanché is a world leading provider of low-carbon footprint energy storage solutions based on lithium-ion cell technology. Established in 1909 in Yverdon-les-Bains, Switzerland, Leclanché’s history and heritage is rooted in battery and energy storage innovation. The company’s Swiss culture for precision and quality, together with its production facilities in Germany, make Leclanché the partner of choice for companies seeking the very best in battery performance and who are pioneering positive changes in how energy is produced, distributed and consumed around the world. Leclanché is organised into three business units: energy storage solutions, e-Mobility solutions and specialty battery systems. The company currently employs over 350 people with representative offices in eight countries around the world. Leclanché is listed on the Swiss Stock Exchange (SIX: LECN).

SIX Swiss Exchange : ticker symbol LECN | ISIN CH 011 030 311 9

Disclaimer

This press release contains certain forward-looking statements relating to Leclanché's business, which can be identified by terminology such as "strategic", "proposes", "to introduce", "will", "planned", "expected", "commitment", "expects", "set", "preparing", "plans", "estimates", "aims", "would", "potential", "awaiting", "estimated", "proposal", or similar expressions, or by expressed or implied discussions regarding the ramp up of Leclanché's production capacity, potential applications for existing products, or regarding potential future revenues from any such products, or potential future sales or earnings of Leclanché or any of its business units. You should not place undue reliance on these statements. Such forward-looking statements reflect the current views of Leclanché regarding future events, and involve known and unknown risks, uncertainties and other factors that may cause actual results to be materially different from any future results, performance or achievements expressed or implied by such statements. There can be no guarantee that Leclanché's products will achieve any particular revenue levels. Nor can there be any guarantee that Leclanché, or any of the business units, will achieve any particular financial results.

Media contacts: 

Switzerland / Europe: 
Thierry Meyer
T: +41 (0) 79 785 35 81
E-Mail: tme@dynamicsgroup.ch

Germany:
Christoph Miller
T: +49 (0) 711 947 670
E-Mail: leclanche@sympra.de

Investor contacts:
Pierre Blanc
T: +41 (0) 24 424 65 00
E-Mail: invest.leclanche@leclanche.com