# EDGAR Filing Document

**Accession Number:** 0001802528
**File Stem:** 0001104659-26-060292
**Filing Date:** 2026-5
**Character Count:** 12172
**Document Hash:** f574a167d34f502f4cc6a5ad7f6a76b7
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-26-060292.hdr.sgml**: 20260513

**ACCESSION NUMBER**: 0001104659-26-060292

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

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20260513

**DATE AS OF CHANGE**: 20260513

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Viridian Therapeutics, Inc.\DE
- **CENTRAL INDEX KEY:** 0001590750
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 471187261
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-88625
- **FILM NUMBER:** 26973891

**BUSINESS ADDRESS:**
- **STREET 1:** 221 CRESCENT STREET
- **STREET 2:** SUITE 103A
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02453
- **BUSINESS PHONE:** 617.272.4600

**MAIL ADDRESS:**
- **STREET 1:** 221 CRESCENT STREET
- **STREET 2:** SUITE 103A
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02453

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** MIRAGEN THERAPEUTICS, INC.
- **DATE OF NAME CHANGE:** 20170213

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** MIRAGEN THERAPEUTICS, INC.
- **DATE OF NAME CHANGE:** 20170213

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** SIGNAL GENETICS, INC.
- **DATE OF NAME CHANGE:** 20140710
**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. 8)**

**Viridian Therapeutics, Inc.\DE**

*(Name of Issuer)*

**Common Stock, $0.01 par value per share**

*(Title of Class of Securities)*

**—**

*(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)*

**05/11/2026**

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

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 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>**17201800.00** |
| 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>**17201800.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**17201800.00** | Aggregate amount beneficially owned by each reporting person<br>**17201800.00** | |
| 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>**14.04%** | Percent of class represented by amount in Row (11)<br>**14.04%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IA** | Type of Reporting Person (See Instructions)<br>**IA** | |

---

**Comment for Reporting Person:** The securities include (i) 5,090,928 shares of common stock, $0.01 par value per share (the "Common Stock") and (ii) an aggregate of 12,110,872 shares of Common Stock issuable upon conversion of 133,191 shares of Series A Non-Voting Convertible Preferred Stock, par value $0.01 per share (the "Series A Preferred Stock") and 48,463 shares of Series B Non-Voting Convertible Preferred Stock, par value $0.01 per share (the "Series B Preferred Stock"), the conversion of each of which is subject to a beneficial ownership limitation of 19.99% of the outstanding Common Stock.

Row 13 is based on 122,538,554 shares of Common Stock outstanding as of May 11, 2026, consisting of (i) 110,427,682 shares of Common Stock outstanding as of May 11, 2026, as reported in the Company's final prospectus supplement filed pursuant to Rule 424(b)(5) dated May 6, 2026 and (ii) an aggregate of 12,110,872 shares of Common Stock issuable upon conversion of 133,191 shares of Series A Preferred Stock and 48,463 shares of Series B Preferred Stock held by the Reporting Persons.

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 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>**17201800.00** |
| 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>**17201800.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**17201800.00** | Aggregate amount beneficially owned by each reporting person<br>**17201800.00** | |
| 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>**14.04%** | Percent of class represented by amount in Row (11)<br>**14.04%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

**Comment for Reporting Person:** The securities include (i) 5,090,928 shares of Common Stock and (ii) an aggregate of 12,110,872 shares of Common Stock issuable upon conversion of 133,191 shares of Series A Preferred Stock and 48,463 shares of Series B Preferred Stock, the conversion of each of which is subject to a beneficial ownership limitation of 19.99% of the outstanding Common Stock.

Row 13 is based on 122,538,554 shares of Common Stock outstanding as of May 11, 2026, consisting of (i) 110,427,682 shares of Common Stock outstanding as of May 11, 2026, as reported in the Company's final prospectus supplement filed pursuant to Rule 424(b)(5) dated May 6, 2026 and (ii) an aggregate of 12,110,872 shares of Common Stock issuable upon conversion of 133,191 shares of Series A Preferred Stock and 48,463 shares of Series B Preferred Stock held by the Reporting Persons.

**Item 1. Security and Issuer**

**(a) Title of Class of Securities:**
Common Stock, $0.01 par value per share

**(b) Name of Issuer:**
Viridian Therapeutics, Inc.\DE

**(c) Address of Issuer's Principal Executive Offices:**
221 Crescent Street, Suite 103A, Waltham, MA, 02453

This Amendment No. 8 amends and supplements the statement on Schedule 13D originally filed with the Securities and Exchange Commission on January 5, 2021, Amendment No. 1 filed on September 23, 2021, Amendment No. 2 filed on August 19, 2022, Amendment No. 3 filed on November 3, 2023, Amendment No. 4 filed on January 24, 2024, Amendment No. 5 filed on April 1, 2024, Amendment No. 6 filed on September 17, 2024, and Amendment No. 7 filed on October 27, 2025 (as amended, the "Statement" or the "Schedule 13D") by the Reporting Persons with respect to the common stock, $0.01 par value ("Common Stock"), of Viridian Therapeutics, Inc. (the "Company"). Unless otherwise defined herein, capitalized terms used in this Amendment No. 8 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 referenced in Item 3 for investment purposes.

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

**(a)**
The information in rows 11 and 13 of each of the cover pages (including the explanatory note in the "Comments") of this Amendment No. 8 is incorporated by reference herein.

**(b)**
The information in rows 7 through 10 of each of the cover pages of this Amendment No. 8 is incorporated by reference herein.

**(c)**
On May 11, 2026, Fund II purchased in the Offering a total of 1,176,470 shares of Common Stock of the Company at a purchase price of $17 per share for an aggregate purchase price of $19,999,990.00.

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

Lock-Up Agreement

In connection with the Offering that closed on May 11, 2026, the Fund II entered into a customary lock-up letter agreement (the "Lock-Up Agreement") with Jefferies LLC, Leerink Partners LLC, and Goldman Sachs & Co. LLC as the representatives of the underwriters (the "Representatives") to an underwriting agreement with the Company. Pursuant to the Lock-Up Agreement, Fund II agreed to refrain from selling shares of the Company's securities without the consent of the Representatives, and other customary lock-up conditions, for a period of 60 days from the date of the Company's final prospectus supplement related to the offering.

The foregoing description of the Lock-Up Agreement does not purport to be complete and is qualified in its entirety by reference to the form of the Lock-Up Agreement, which is filed as Exhibit 99.2 to this Schedule 13D and incorporated herein by reference.

### 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:** 05/13/2026

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:** 05/13/2026