# EDGAR Filing Document

**Accession Number:** 0002123881
**File Stem:** 0001104659-26-034498
**Filing Date:** 2026-3
**Character Count:** 5504
**Document Hash:** 32e46af40da0d2ed99c5170e834733fc
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-26-034498.hdr.sgml**: 20260325

**ACCESSION NUMBER**: 0001104659-26-034498

**CONFORMED SUBMISSION TYPE**: 3

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20260318

**FILED AS OF DATE**: 20260325

**DATE AS OF CHANGE**: 20260325

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Teyssedou Lenaic Nathanael
- **CENTRAL INDEX KEY:** 0002123881

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 3
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-39179
- **FILM NUMBER:** 26792383

**MAIL ADDRESS:**
- **ADDRESS IS A NON US LOCATION:** YES
- **STREET 1:** CHEMIN DES MINES 9
- **CITY:** GENEVA
- **PROVINCE COUNTRY:** V8
- **ZIP:** CH-1202
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Addex Therapeutics Ltd.
- **CENTRAL INDEX KEY:** 0001574232
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 000000000
- **STATE OF INCORPORATION:** V8
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **STREET 1:** CHEMIN DES MINES 9
- **CITY:** GENEVA
- **STATE:** V8
- **ZIP:** CH-1202
- **BUSINESS PHONE:** 01141228841555

**MAIL ADDRESS:**
- **STREET 1:** CHEMIN DES MINES 9
- **CITY:** GENEVA
- **STATE:** V8
- **ZIP:** CH-1202

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM 3

### INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Teyssedou Lenaic Nathanael<br><sub>(Last) (First) (Middle)</sub><br>CHEMIN DES MINES 9<br><sub>(Street)</sub><br>GENEVA, SWITZERLAND CH-1202<br><sub>(City) (State) (Zip)</sub> | **3. Issuer Name and Ticker or Trading Symbol**<br>Addex Therapeutics Ltd. [ ADXN ] | **5. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  |
| **2. Date of Event Requiring Statement (Month/Day/Year)**<br>2026-03-18 | **4. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director   [ ] 10% Owner<br>[X] Officer (give title below)   [ ] Other (specify below)<br>_PRINCIPAL ACCOUNTING OFFICER_ | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[X] Form filed by One Reporting Person<br>[ ] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities Beneficially Owned

---

|  |  |  |  |
| --- | --- | --- | --- |
| 1. Title of Security | 2. Amount of Securities Beneficially Owned | 3. Ownership Form | 4. Nature of Indirect Beneficial Ownership |

---

## Table II - Derivative Securities Beneficially Owned

---

|  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 3. Title and Amount of Underlying Securities | 3. Title and Amount of Underlying Securities | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
| Stock-option (Right to Buy) | 2018-01-01<sup>(1)</sup> | 2027-12-31 | Common Stock | 37770 | 0.166<sup>(2)</sup> | D |  |
| Stock-option (Right to Buy) | 2018-06-01<sup>(1)</sup> | 2028-05-31 | Common Stock | 59530 | 0.166<sup>(2)</sup> | D |  |
| Stock-option (Right to Buy) | 2020-04-01<sup>(1)</sup> | 2030-03-31 | Common Stock | 10000 | 0.166<sup>(2)</sup> | D |  |
| Stock-option (Right to Buy) | 2021-05-17<sup>(1)</sup> | 2031-05-16 | Common Stock | 30000 | 0.166<sup>(2)</sup> | D |  |
| Stock-option (Right to Buy) | 2022-04-12<sup>(1)</sup> | 2032-04-11 | Common Stock | 65620 | 0.166<sup>(2)</sup> | D |  |
| Stock-option (Right to Buy) | 2022-10-05<sup>(1)</sup> | 2032-10-04 | Common Stock | 90529 | 0.166<sup>(2)</sup> | D |  |
| Stock-option (Right to Buy) | 2023-05-12<sup>(1)</sup> | 2033-05-11 | Common Stock | 208974 | 0.055<sup>(2)</sup> | D |  |
| Stock-option (Right to Buy) | 2024-01-08<sup>(1)</sup> | 2034-01-07 | Common Stock | 100485 | 0.064<sup>(2)</sup> | D |  |

---

### Footnotes:

(1) The stock-options vest on equal monthly installments over a 4-year period beginning at the exercisable date. Each stock-option grants to right to purchase one ADXN share listed on SIX Swiss Exchange.

(2) The exercise price is reported in U.S. dollars and reflects the conversion from CHF to USD at an exchange rate of $1.2769 per CHF 1.00 as of March 12, 2026.

**Signature:** /s/ Lenaic Nathanael Teyssedou  
**Date:** 2026-03-18

### Remarks:

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

**Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.**