Ad Hoc Announcement Pursuant to Art. 53 LR

Geneva, Switzerland, June 5, 2026 - Addex Therapeutics (SIX and Nasdaq: ADXN), a clinical-stage biopharmaceutical company focused on developing a portfolio of novel small molecule allosteric modulators for neurological disorders, today announced that its 2026 Annual General Meeting will take place on Monday June 29, 2026 at 11:00 am CEST at the Campus Biotech, Chemin des Mines 9, 1202 Geneva (doors open at 10:30 am).

Agenda

1.   Approval of the Annual Report, the Annual Financial Statements and the Consolidated Financial Statements for the business year 2025

2.   Consultative vote on the Compensation Report for the business year 2025

3.   Appropriation of the results

4.   Discharge of the members of the Board of Directors and of the Executive Management

5.   Re-elections of the members of the Board of Directors and re-election of the Chairman of the Board of Directors

5.1.    Re-election of Vincent Lawton as member and Chairman of the Board of Directors

5.2.    Re-election of Raymond Hill as member of the Board of Directors

5.3.    Re-election of Timothy Dyer as member of the Board of Directors

5.4.    Re-election of Roger Mills as member of the Board of Directors

5.5.    Re-election of Jake Nunn as member of the Board of Directors

5.6.    Re-election of Isaac Manke as member of the Board of Directors

6.   Re-elections of the members of the Compensation Committee

6.1.    Re-election of Vincent Lawton as member of the Compensation Committee

6.2.    Re-election of Raymond Hill as member of the Compensation Committee

7.   Re-election of the Auditor

8.   Re-election of the Independent Voting Rights Representative

9.   Amendments to the Articles of Association

9.1.    Increase of the capital band (article 3b of the Articles of Association)

9.2.    Increase of the conditional share capital (article 3c of the Articles of Association)

10.   Approval of the compensation of the members of the Board of Directors and of the Executive Management

10.1.     Compensation of the members of the Board of Directors

10.2.     Compensation of the members of the Executive Management

11.   Miscellaneous

The full invitation to the AGM 2026 may be found in the General Meetings section of the Company's website here.

About Addex Therapeutics:

Addex Therapeutics is a clinical-stage biopharmaceutical company focused on developing a portfolio of novel small molecule allosteric modulators for neurological disorders. Addex's lead drug candidate, dipraglurant (mGlu5 negative allosteric modulator or NAM), is under evaluation for future development in brain injury recovery, including post-stroke and traumatic brain injury recovery. Addex's partner, Indivior, has selected a GABAB PAM drug candidate for development in substance use disorders and has successfully completed IND enabling studies. Addex is advancing an independent GABAB PAM program for chronic cough. Addex holds a 20% equity interest in a private spin out company, Neurosterix US Holdings LLC, which is advancing a portfolio of allosteric modulator programs, including M4 PAM for schizophrenia, psychosis and mood-related disorders and mGlu7 NAM for mood disorders. In addition, Addex has invested in Stalicla, a private Swiss company pioneering a precision medicine approach for neurodevelopmental and neuropsychiatric disorders.

Addex shares are listed on the SIX Swiss Exchange and American Depositary Shares representing its shares are listed on the NASDAQ Capital Market, and trade under the ticker symbol "ADXN" on each exchange. For more information, visit www.addextherapeutics.com.

Contacts:

Tim Dyer

Chief Executive Officer

Telephone: +41 22 884 15 55

PR@addextherapeutics.com

Mike Sinclair

Partner, Halsin Partners

+44 (0)7968 022075

msinclair@halsin.com

Addex Forward Looking Statements:

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including statements about the intended use of proceeds of the offering. The words "may," "will," "could," "would," "should," "expect," "plan," "anticipate," "intend," "believe," "estimate," "predict," "project," "potential," "continue," "target" and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Any forward-looking statements in this press release, are based on management's current expectations and beliefs and are subject to a number of risks, uncertainties and important factors that may cause actual events or results to differ materially from those expressed or implied by any forward-looking statements contained in this press release, including, without limitation, uncertainties related to market conditions. These and other risks and uncertainties are described in greater detail in the section entitled "Risk Factors" in Addex Therapeutics' Annual Report on Form 20-F, prospectus and other filings that Addex Therapeutics may make with the SEC in the future. Any forward-looking statements contained in this press release represent Addex Therapeutics' views only as of the date hereof and should not be relied upon as representing its views as of any subsequent date. Addex Therapeutics explicitly disclaims any obligation to update any forward-looking statements.

Addex Convenes Annual General Meeting 2026