Addex CEO Dyer holds 19.1M shares, 8.89% stake

Addex Therapeutics Ltd. (ADXN) received an amended Schedule 13D (Amendment No. 9) from its Chief Executive Officer and director, Timothy Mark Dyer, updating his ownership position following dilution from additional share issuances.

Rhea-AI Filing Summary

Addex Therapeutics Ltd. (ADXN) received an amended Schedule 13D (Amendment No. 9) from its Chief Executive Officer and director, Timothy Mark Dyer, updating his ownership position following dilution from additional share issuances. As of August 26, 2026, Dyer beneficially owns 19,095,510 ordinary shares of Addex, including shares underlying options exercisable within 60 days.

This stake represents approximately 8.89% of Addex’s ordinary shares, based on 210,292,217 ordinary shares outstanding as reported on August 26, 2026. His holdings consist of 16,848,979 issued shares and 2,246,531 shares issuable upon option exercise. The securities were acquired over many years through founder shares, private placements, option exercises, and share and option compensation for his service as CEO. Dyer reports sole voting and dispositive power over all of these shares and states he has no present specific plans for corporate actions, while reserving the right to change his intentions.

Key Figures

Beneficial ownership: 19,095,510 Shares Issued ordinary shares held: 16,848,979 Shares Shares issuable upon exercise of options: 2,246,531 Shares +5 more

8 metrics

Beneficial ownership 19,095,510 Shares Shares beneficially owned by Timothy Mark Dyer as of August 26, 2026

Issued ordinary shares held 16,848,979 Shares Ordinary shares directly held by Timothy Mark Dyer

Shares issuable upon exercise of options 2,246,531 Shares Shares underlying options exercisable within 60 days of August 26, 2026

Ownership percentage 8.89 % Percentage of Addex Therapeutics ordinary shares beneficially owned by Timothy Mark Dyer

Ordinary shares outstanding 210,292,217 Shares Addex Therapeutics ordinary shares outstanding as of August 26, 2026

Option strike price CHF 0.13 per share Deferred strike price for multiple option exercises on October 26, 2022

Option strike price CHF 0.043 per share Deferred strike price for options to purchase 7,008,033 Shares exercised on November 27, 2023

Exercise price of 2024 option grant CHF 0.05 per share Exercise price for option granted January 8, 2024 to purchase 3,369,796 Shares

Key Terms

beneficially owns, sole voting power, sole dispositive power, American Depositary Shares, +2 more

6 terms

beneficially owns regulatory

"As of the date hereof, Reporting Person beneficially owns 19,095,510 Shares"

Beneficially owns means a person or entity enjoys the economic benefits and control of a security even if the legal title or registration is held in another name. Think of it like having the keys and profits from a car that is registered to a friend: you use it, benefit from it, and make decisions about it even though the official paperwork lists someone else. For investors, this matters because it reveals who truly controls shares, affects voting power, potential conflicts of interest, and regulatory disclosure obligations.

sole voting power regulatory

"Reporting Person may be deemed to hold sole voting and dispositive power"

Sole voting power is the exclusive right to cast votes attached to a shareholder’s stock without needing approval from anyone else. Like holding the only remote control for a TV, it lets that holder decide corporate matters such as board members, mergers, and policy changes, making it important to investors because it concentrates control and can strongly influence a company’s strategy and the value of its shares.

sole dispositive power regulatory

"Reporting Person may be deemed to hold sole voting and dispositive power"

Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.

American Depositary Shares financial

"Title of Class of Securities: American Depositary Shares, each representing 120 ordinary shares"

American depositary shares (ADSs) are a way for investors in the United States to buy shares of foreign companies without dealing with international markets directly. They represent ownership in a foreign company's stock and are traded on U.S. stock exchanges, making it easier for American investors to buy, sell, and own parts of companies from around the world.

Schedule 13D regulatory

"This Amendment No.9 amends and restates the Statement on initially filed"

A Schedule 13D is a legal document that investors file with regulators when they buy a large enough stake in a company to potentially influence its management or decisions. It provides details about the investor’s intention, ownership stake, and plans, helping other investors understand who is gaining control and what their motives might be.

private placement financial

"Reporting Person acquired 36,364 Shares at a purchase price of CHF 2.75 per share through participation in a private placement"

A private placement is a sale of securities directly to a selected group of investors, typically institutions or accredited investors, instead of through a public offering. It lets a company raise money faster and with fewer regulatory steps; for existing shareholders it matters because the newly issued shares, often sold at a discount, increase the share count and can dilute their ownership.

FAQ

How many Addex Therapeutics (ADXN) shares does Timothy Mark Dyer currently beneficially own?

As of August 26, 2026, Timothy Mark Dyer beneficially owns 19,095,510 Addex Therapeutics ordinary shares, including 16,848,979 issued shares and 2,246,531 shares issuable upon exercise of options exercisable within 60 days.

What percentage of Addex Therapeutics (ADXN) does Timothy Mark Dyer own according to this Schedule 13D/A?

Timothy Mark Dyer’s beneficial ownership represents approximately 8.89% of Addex Therapeutics’ ordinary shares, based on 210,292,217 ordinary shares outstanding as of August 26, 2026, as reported by the company in a Form 6-K press release.

How is Timothy Mark Dyer’s Addex Therapeutics (ADXN) stake composed between shares and options?

His stake consists of 16,848,979 ordinary shares and 2,246,531 additional shares issuable upon exercise of stock options that are exercisable within 60 days of August 26, 2026, all of which he reports as beneficially owned.

Why did Timothy Mark Dyer file Amendment No. 9 to his Schedule 13D for ADXN?

Amendment No. 9 was filed to update the percentage of Addex Therapeutics securities beneficially owned by Timothy Mark Dyer due to dilution from additional share sales by the company, which increased the number of shares outstanding and changed his reported ownership percentage by more than 1%.

What is the total number of Addex Therapeutics (ADXN) ordinary shares outstanding used in this ownership calculation?

The ownership percentage is calculated using 210,292,217 Addex Therapeutics ordinary shares outstanding as of August 26, 2026, as reported in a press release furnished on Form 6-K (File No. 001-39179).

Does Timothy Mark Dyer have control over his Addex Therapeutics (ADXN) shares?

Yes. Timothy Mark Dyer reports sole voting power and sole dispositive power over all 19,095,510 shares that he beneficially owns, with no shared voting or dispositive power reported.

How did Timothy Mark Dyer acquire his Addex Therapeutics (ADXN) holdings over time?

He acquired shares as a founder, through private placements funded with personal funds, and through extensive stock option grants and share compensation for serving as Chief Executive Officer, with many options exercised at strike prices including CHF 0.13 and CHF 0.043 per share.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 08/27/2026 - 06:07 AM Accepted by SEC EDGAR 08/27/2026 - 06:00 AM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 9)

Addex Therapeutics Ltd.

(Name of Issuer)

American Depositary Shares, each representing 120 ordinary shares Ordinary shares

(Title of Class of Securities)

00654J206

(CUSIP Number)

Timothy Mark Dyer
c/o Addex Therapeutics Ltd, Chemin des Mines 9
Geneva, V8, CH-1202
41 22 884 1555

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

08/26/2026

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

schemaVersion:

SCHEDULE 13D

CUSIP Number(s): 00654J206

1

Name of reporting person

Timothy Mark Dyer

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

PF, OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

SWITZERLAND

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 19,095,510.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 19,095,510.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

19,095,510.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

8.98 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

Consists of 16,848,979 ordinary shares and 2,246,531 shares issuable upon exercise of options exercisable within 60 days of Agust 26, 2026. (2) Represents the percentage ownership based on 210,292,217 ordinary shares of Addex Therapeutics Ltd outstanding as of August 26, 2026, as reported in the press release on form 6K (file No.001-39179) filed on August 26, 2026.

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: American Depositary Shares, each representing 120 ordinary shares Ordinary shares
(b)	Name of Issuer: Addex Therapeutics Ltd.
(c)	Address of Issuer's Principal Executive Offices: Chemin des Mines 9, Geneva, SWITZERLAND , CH-1202.
Item 1 Comment: This Schedule 13D relates to the ordinary shares, nominal value CHF 0.01 per share (the "Shares"), of Addex Therapeutics Ltd (the "Issuer"). The Issuer's principal executive office is located at Chemin des Mines 9, CH- 1202 Geneva, Switzerland. This Amendment No.9 ("Amendment No.9") amends and restates the Statement on Schedule 13D initially filed on November 3, 2020 and amended on June 23, 2025 (as amended, the "Original Schedule 13D"). This Amendment No.9 is being filed to update the aggregate percentage of the class of securities of the Issuer owned by the Reporting Person due to the dilution caused by the Issuer's additional sales of shares from time to time since the filing of the Original Schedule 13D. The Issuer reported increased number of outstanding shares as of August 26, 2026 in the press release on form 6K (file No.001-39179) filed on August 26, 2026, causing a variation of more than one (1%) from the percentages reported in the Original Schedule 13D.
Item 2.	Identity and Background
(a)	Timothy Mark Dyer, an individual ("Reporting Person").
(b)	The business address of Reporting Person is c/o Addex Therapeutics Ltd, Chemin des Mines 9, CH- 1202 Geneva, Switzerland.
(c)	Reporting Person is the Chief Executive Officer and a member of the Board of Directors of the Issuer.
(d)	During the last five years, Reporting Person has not been (1) convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or (2) a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding has been or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.
(e)	During the last five years, Reporting Person has not been (1) convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or (2) a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding has been or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.
(f)	Reporting Person is a citizen of Switzerland and United Kingdom.
Item 3.	Source and Amount of Funds or Other Consideration
	Reporting Person is deemed to beneficially own 19,095,510 Shares of the Issuer as reflected in this Schedule 13D. Prior to May 21, 2007, Reporting Person acquired 7,811 founder shares at a purchase price of CHF 1.00. The source of funds for such purchase was Reporting Person's personal funds. On August 9, 2013, Reporting Person acquired 36,364 Shares at a purchase price of CHF 2.75 per share through participation in a private placement. The source of funds for such purchase was Reporting Person's personal funds. On June 30, 2014, Reporting Person was granted stock options from the Issuer to purchase 400,000 Shares issuable upon exercise of options as compensation for his service as Chief Executive Officer of the Issuer. On October 26, 2022, Reporting Person exercised the options and acquired 400,000 Shares that are all freely tradable. The deferred strike price was CHF 0.13 for each share acquired. On July 1, 2014, Reporting Person received 18,143 Shares as compensation for his service as Chief Executive Officer of the Issuer. On July 14, 2014, Reporting Person received 24,588 Shares as compensation for his service as Chief Executive Officer of the Issuer. On January 7, 2015, Reporting Person received 17,063 Shares as compensation for his service as Chief Executive Officer of the Issuer. On March 6, 2015, Reporting Person acquired 33,333 Shares at a purchase price of CHF 3.00 per share during a private placement. The source of funds for such purchase was Reporting Person's personal funds. On July 28, 2015, Reporting Person received 17,149 Shares as compensation for his service as Chief Executive Officer of the Issuer. On January 28, 2016, Reporting Person received 17,461 Shares as compensation for his service as Chief Executive Officer of the Issuer. On August 2, 2016, Reporting Person received 20,263 Shares as compensation for his service as Chief Executive Officer of the Issuer. On January 16, 2017, Reporting Person received 23,001 Shares as compensation for his service as Chief Executive Officer of the Issuer. On February 28, 2017, Reporting Person was granted stock options from the Issuer to purchase 229,480 Shares issuable upon exercise of options as compensation for his service as Chief Executive Officer of the Issuer. On October 26, 2022, Reporting Person exercised the options and acquired 229,480 Shares that are all freely tradable. The deferred strike price was CHF 0.13 for each share acquired. On July 28, 2017, Reporting Person received 23,187 Shares as compensation for his service as Chief Executive Officer of the Issuer. On December 23, 2017, Reporting Person was granted stock options from the Issuer to purchase 1,052,250 Shares. On October 26, 2022, Reporting Person exercised the options and acquired 1,052,250 Shares that are all freely tradable. The deferred strike price was CHF 0.13 for each share acquired. On December 23, 2017, Reporting Person acquired 108,000 Shares through the exercise of options of which 53,000 and 55,000 were received on June 1, 2010, and November 15, 2011, respectively. The exercise price was CHF 1.00 for the Shares acquired and the source of funds for such purchase was Reporting Person's personal funds. On January 4, 2018, Reporting Person received 24,519 Shares as compensation for his service as Chief Executive Officer of the Issuer. On August 15, 2018, Reporting Person received 18,226 Shares as compensation for his service as Chief Executive Officer of the Issuer. On March 28, 2018, Reporting Person acquired 31,948 Shares at a purchase price of CHF 3.13 per share through participation in a private placement. The source of funds for such purchase was Reporting Person's personal funds. On June 1, 2018, Reporting Person was granted stock options from the Issuer to purchase 1,199,662 Shares. On October 26, 2022, Reporting Person exercised the options and acquired 1,199,662 Shares that are all freely tradable. The deferred strike price was CHF 0.13 for each share acquired. On January 1, 2019, Reporting Person was granted stock options from the Issuer to purchase 243,506 Shares. On October 26, 2022, Reporting Person exercised the options and acquired 243,506 Shares that are all freely tradable. The deferred strike price was CHF 0.13 for each share acquired. On January 4, 2019, Reporting Person received 14,136 Shares as compensation for his service as Chief Executive Officer of the Issuer. On April 1, 2020, Reporting Person was granted stock options from the Issuer to purchase 698,011 Shares. On October 26, 2022, Reporting Person exercised the options and acquired 698,011 Shares that are all freely tradable. The deferred strike price was CHF 0.13 for each Share acquired. On May 17, 2021, Reporting Person was granted stock options from the Issuer to purchase 700,000 Shares. On October 26, 2022, Reporting Person exercised the options and acquired 700,000 Shares that are all freely tradable. The deferred strike price was CHF 0.13 for each share acquired. On April 12, 2022, Reporting Person was granted stock options from the Issuer to purchase 2,051,972 Shares. On October 26, 2022, Reporting Person exercised the options and acquired 2,051,972 Shares that are all freely tradable. The deferred strike price was CHF 0.13 for each share acquired. On October 5, 2022, Reporting Person was granted stock options from the Issuer to purchase 2,830,873 Shares. On October 26, 2022, Reporting Person exercised the options and acquired 2,830,873 Shares. Of these shares 58,977 are not freely tradable as of August 26, 2026. The deferred strike price was CHF 0.13 for each share acquired. On May 12, 2023, Reporting Person was granted stock options from the Issuer to purchase 7,008,033 Shares. On November 27, 2023, Reporting Person exercised the options and acquired 7,008,033 Shares. Of these shares 1,168,005 are not freely tradable as of August 26, 2026. The deferred strike price was CHF 0.043 for each share acquired. On January 8, 2024, Reporting Person was granted a stock option from the Issuer to purchase 3,369,796 shares at an exercise price of CHF 0.05. The shares underlying this option vest in 48 equal monthly installments, subject to Timothy Mark Dyer's continuous service as Chief Executive Officer of the issuer. As of August 26, 2026, 2,246,531 Shares are issuable upon exercise of options as compensation for his service as Chief Executive Officer of the Issuer. Unless specifically stated above, Reporting Person paid no compensation for the Shares.
Item 4.	Purpose of Transaction
	The Reporting Person acquired the securities of the Issuer at founding, through the exercise of options, acquisitions through participation in private placements and in consideration for his services as Chief Executive Officer of the Issuer. The reporting person also received shares issuable upon exercise of options. The terms of the Reporting Person's employment arrangements for 2025 were set forth in the Issuer's Annual Report on Form 20-F for such period filed by the Issuer with the Securities and Exchange Commission on May 15, 2026. Except in respect of such employment arrangements as set forth therein, the Reporting Person does not have any present plans which relate to or would result in: However, the Reporting Person reserves the right to change its plans at any time, as it deems appropriate, in light of its ongoing evaluation of (i) its business and liquidity objectives? (ii) the Issuer's financial condition, business, operations, competitive position, prospects and/or Share price? (iii) industry, economic and/or securities markets conditions? (iv) alternative investment opportunities? and (v) other relevant factors.
Item 5.	Interest in Securities of the Issuer
(a)	As of the date hereof, Reporting Person beneficially owns 19,095,510 Shares, which represents approximately 8.89% of the Issuer's Shares, consisting of (i) 16,848,979 Shares (ii) 2,246,531 Shares issuable upon exercise of options exercisable within 60 days of August 26, 2026.
(b)	Reporting Person may be deemed to hold sole voting and dispositive power over his 19,095,510 Shares of the Issuer.
(c)	Other than the acquisition of the shares as reported herein, and as described under Item 4, Reporting Person has not effected any transactions in the shares of the Issuer during the past 60 days or since the most recent filing of Schedule 13D, whichever is less.
(d)	To the best knowledge of Reporting Person, no person other than the Reporting Person has the right to receive, or the power to direct the receipt of, dividends from, or the proceeds from the sale of the 19,095,510 Shares reported in Item 5(a).
(e)	Not applicable.
Item 6.	Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer
	The information furnished in Item 3 is incorporated into this Item 6 by reference.
Item 7.	Material to be Filed as Exhibits.
	Not applicable.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Timothy Mark Dyer

Signature:	/s/ Timothy Mark Dyer
Name/Title:	Timothy Mark Dyer
Date:	08/27/2026