# EDGAR Filing Document

**Accession Number:** 0001622229
**File Stem:** 0001104659-25-067760
**Filing Date:** 2025-7
**Character Count:** 11840
**Document Hash:** 03df02e3b7affa14e2a4ef3ddda3e15b
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-25-067760.hdr.sgml**: 20250714

**ACCESSION NUMBER**: 0001104659-25-067760

**CONFORMED SUBMISSION TYPE**: SCHEDULE 13D/A

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20250714

**DATE AS OF CHANGE**: 20250714

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Cogent Biosciences, Inc.
- **CENTRAL INDEX KEY:** 0001622229
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 465308248
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-90431
- **FILM NUMBER:** 251122052

**BUSINESS ADDRESS:**
- **STREET 1:** 275 WYMAN STREET
- **STREET 2:** 3RD FLOOR
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02451
- **BUSINESS PHONE:** 617-945-5576

**MAIL ADDRESS:**
- **STREET 1:** 275 WYMAN STREET
- **STREET 2:** 3RD FLOOR
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02451

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Unum Therapeutics Inc.
- **DATE OF NAME CHANGE:** 20180402

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Unum Therapeutics, Inc.
- **DATE OF NAME CHANGE:** 20141014
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Fairmount Funds Management LLC
- **CENTRAL INDEX KEY:** 0001802528

**ORGANIZATION NAME:**
- **EIN:** 364841215
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A

**BUSINESS ADDRESS:**
- **STREET 1:** 200 BARR HARBOR DRIVE
- **STREET 2:** SUITE 400
- **CITY:** WEST CONSHOHOCKEN
- **STATE:** PA
- **ZIP:** 19428
- **BUSINESS PHONE:** 267-262-5300

**MAIL ADDRESS:**
- **STREET 1:** 200 BARR HARBOR DRIVE
- **STREET 2:** SUITE 400
- **CITY:** WEST CONSHOHOCKEN
- **STATE:** PA
- **ZIP:** 19428

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

## SCHEDULE 13D

### Under the Securities Exchange Act of 1934

**(Amendment No. 7)**

**Cogent Biosciences, Inc.**

*(Name of Issuer)*

**Common Stock, $0.001 par value**

*(Title of Class of Securities)*

**19240Q201**

*(CUSIP Number)*

**Ms. Erin O'Connor**<br>Fairmount Funds Management LLC<br>200 Barr Harbor Drive, Suite 400<br>West Conshohocken PA 19428<br>(267) 262-5300

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

**07/10/2025**

*(Date of Event Which Requires Filing of this Statement)*

| **CUSIP No.** | **19240Q201** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Fairmount Funds Management LLC** | Name of reporting person<br>**Fairmount Funds Management LLC** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**14324918.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**14324918.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**14324918.00** | Aggregate amount beneficially owned by each reporting person<br>**14324918.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**9.9%** | Percent of class represented by amount in Row (11)<br>**9.9%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IA** | Type of Reporting Person (See Instructions)<br>**IA** | |

---

**Comment for Reporting Person:** The securities include (a) 9,003,418 shares of common stock, $0.001 par value ("Common Stock"), and (b) 5,325,500 shares of Common Stock issuable upon conversion of approximately 21,302 shares of Series A Convertible Preferred Stock, par value $0.001 per share (the "Series A Preferred Stock") directly held by Fairmount Healthcare Fund II L.P. ("Fund II"). The securities exclude shares of Common Stock issuable upon conversion of shares of Series A Preferred Stock held directly by Fund II in excess of the beneficial ownership limitation of 9.9%.

Row 13 is based on 139,412,010 shares of Common Stock outstanding, consisting of 113,856,454 shares of Common Stock outstanding as of May 2, 2025 plus 25,555,556 shares of Common Stock sold in the Offering (as defined below).

| **CUSIP No.** | **19240Q201** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Fairmount Healthcare Fund II GP LLC** | Name of reporting person<br>**Fairmount Healthcare Fund II GP LLC** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**14324918.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**14324918.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**14324918.00** | Aggregate amount beneficially owned by each reporting person<br>**14324918.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**9.9%** | Percent of class represented by amount in Row (11)<br>**9.9%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**OO** | Type of Reporting Person (See Instructions)<br>**OO** | |

---

**Comment for Reporting Person:** The securities include (a) 9,003,418 shares of Common Stock and (b) 5,325,500 shares of Common Stock issuable upon conversion of approximately 21,302 shares of Series A Preferred Stock directly held by Fund II. The securities exclude shares of Common Stock issuable upon conversion of shares of Series A Preferred Stock held directly by Fund II in excess of the beneficial ownership limitation of 9.9%.

Row 13 is based on 139,412,010 shares of Common Stock outstanding, consisting of 113,856,454 shares of Common Stock outstanding as of May 2, 2025 plus 25,555,556 shares of Common Stock sold in the Offering.

**Item 1. Security and Issuer**

**(a) Title of Class of Securities:**
Common Stock, $0.001 par value

**(b) Name of Issuer:**
Cogent Biosciences, Inc.

**(c) Address of Issuer's Principal Executive Offices:**
275 Wyman Street, 3rd Floor, Waltham, MA, 02451

This Amendment No. 7 amends and supplements the statement on Schedule 13D originally filed with the Securities and Exchange Commission on July 6, 2020, Amendment No. 1 filed on June 21, 2022, Amendment No. 2 filed on June 13, 2023, Amendment No. 3 filed on February 16, 2024, Amendment No. 4 filed on March 27, 2024, Amendment No. 5 filed on April 1, 2024, and Amendment No. 6 filed on June 13, 2024 (as amended, the "Statement" or the "Schedule 13D") by the Reporting Persons with respect to the Common Stock of Cogent Biosciences, Inc. (the "Company"). Unless otherwise defined herein, capitalized terms used in this Amendment No. 7 shall have the meanings ascribed to them in the Statement. Unless amended or supplemented below, the information in the Statement remains unchanged.

**Item 4. Purpose of Transaction**

Item 4 is hereby amended and supplemented as follows:

Fund II purchased the shares of Common Stock referred to in Item 3 for investment purposes.

Lock-up Agreement

Pursuant to lock-up agreements signed in connection with the Offering, Fund II and each director and officer of the Company agreed with the representatives of the underwriters, subject to specified exceptions, not to directly or indirectly offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or otherwise transfer or dispose of any shares of Common Stock beneficially owned (as such term is used in Rule 13d-3 of the Exchange Act) or any other securities so owned that are convertible into or exercisable or exchangeable for Common Stock; or dispose of any shares of Common Stock, options to acquire shares of Common Stock, or securities exchangeable or exercisable for or convertible into shares of Common Stock currently or hereafter owned either of record or beneficially. This restriction terminates after the close of trading of the Common Stock on and including the 60th day after the date of the prospectus supplement relating to the Offering.

**Item 5. Interest in Securities of the Issuer**

**(a)**
See Items 7-11 of the cover pages above and Item 2.

**(b)**
See Items 7-11 of the cover pages above and Item 2.

**(c)**
The following table lists the Reporting Persons' transaction in Common Stock of the Company that was effected in the sixty day period prior to the filing of this Amendment No. 7:

Transaction     Purchaser     Date                     Number of Shares     Price Per Share
Purchase         Fund II          July 10, 2025       2,777,777                  $9.00

The Reporting Persons did not effect any transactions in shares of Series A Preferred Stock in the sixty days prior to the filing of this Amendment No. 7.

**Item 6. Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer.**

Fairmount is entitled to a fee for managing and advising Fund II based upon a percentage of the net asset value of Fund II.

### 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.

**Reporting Person:** Fairmount Funds Management LLC

**Signature:** /s/ Peter Harwin

**Name/Title:** Peter Harwin, Managing Member

**Date:** 07/14/2025

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.

**Reporting Person:** Fairmount Healthcare Fund II GP LLC

**Signature:** /s/ Peter Harwin

**Name/Title:** Peter Harwin, Managing Member

**Date:** 07/14/2025