Fairmount boosts Viridian Therapeutics (VRDN) stake to 14.04% after $20M share purchase

Rhea-AI Filing Summary

Fairmount Funds Management LLC and affiliates updated their ownership disclosure for Viridian Therapeutics, Inc. after a new share purchase. The reporting persons now have voting and dispositive power over 17,201,800 shares of common stock, representing 14.04% of Viridian’s outstanding common stock as of May 11, 2026. This position includes 5,090,928 common shares and 12,110,872 shares issuable upon conversion of Series A and Series B Non-Voting Convertible Preferred Stock, each series subject to a 19.99% beneficial ownership limitation. On May 11, 2026, Fairmount Healthcare Fund II bought 1,176,470 common shares at $17 per share in an underwritten public offering for an aggregate price of $19,999,990, funded with working capital, and agreed to a 60‑day lock-up on sales from the date of the company’s final prospectus supplement.

Insights

Equity ownership and capital markets analyst

Fairmount’s Viridian stake rises to 14.04% via a $20M offering buy.

Fairmount-managed entities now report beneficial ownership of 17,201,800 Viridian Therapeutics common shares, or 14.04% of the company’s outstanding stock as of May 11, 2026. The stake combines existing common shares and convertible preferred shares subject to a 19.99% beneficial ownership limit.

Fund II acquired 1,176,470 new common shares at $17 per share, totaling $19,999,990, in an underwritten public offering. This transaction increases Fairmount’s exposure while the lock-up agreement restricts sales of the securities for 60 days from the date of the final prospectus supplement.

The lock-up, customary in such offerings, temporarily stabilizes Fairmount’s position. Future ownership levels will depend on any conversions of Series A and Series B Non-Voting Convertible Preferred Stock and subsequent transactions disclosed in later filings.

Key Figures

Beneficial ownership: 17,201,800 shares Ownership percentage: 14.04% New shares purchased: 1,176,470 shares +5 more

8 metrics

Beneficial ownership 17,201,800 shares Shares of Viridian common stock beneficially owned by reporting persons

Ownership percentage 14.04% Percent of Viridian common stock outstanding as of May 11, 2026

New shares purchased 1,176,470 shares Viridian common shares bought by Fund II on May 11, 2026

Purchase price per share $17 per share Price paid by Fund II in the May 11, 2026 offering

Aggregate purchase price $19,999,990 Total paid by Fund II for new Viridian common shares

Convertible preferred into common 12,110,872 shares Common shares issuable from Series A and B Preferred held

Shares outstanding baseline 122,538,554 shares Viridian common stock outstanding basis for ownership calculation

Beneficial ownership cap 19.99% Limitation on conversion of Series A and B Preferred

Key Terms

beneficial ownership limitation, Series A Non-Voting Convertible Preferred Stock, Series B Non-Voting Convertible Preferred Stock, underwritten public offering, +2 more

6 terms

beneficial ownership limitation financial

"the conversion of each of which is subject to a beneficial ownership limitation of 19.99% of the outstanding Common Stock"

A beneficial ownership limitation is a rule that caps the percentage of a company’s shares an investor can be treated as owning or controlling for voting, regulatory or tax purposes. It matters to investors because it can restrict how many shares a person or group can buy or vote, affect takeover chances, and influence share liquidity and value — like a speed limit that prevents any single driver from taking over the whole road.

Series A Non-Voting Convertible Preferred Stock financial

"133,191 shares of Series A Non-Voting Convertible Preferred Stock, par value $0.01 per share"

Series A non-voting convertible preferred stock is an early-round ownership share that gives holders priority over common shareholders for payouts and protections, but does not grant voting control. It can be exchanged later for common shares—like a coupon that can be turned into regular stock—allowing investors to share in upside while limiting immediate influence on company decisions; this affects potential returns, dilution for other shareholders, and the balance of control in future financing or sale events.

Series B Non-Voting Convertible Preferred Stock financial

"48,463 shares of Series B Non-Voting Convertible Preferred Stock, par value $0.01 per share"

A Series B non-voting convertible preferred stock is a class of company shares that gives holders financial priority—such as fixed dividends and first claim on assets if the company is sold—while not granting voting rights. It can be converted into regular common shares under set conditions, which matters to investors because conversion can increase upside participation but also dilute existing owners; the preference reduces downside risk like a safety buffer.

underwritten public offering financial

"purchased a total of 1,176,470 shares of Common Stock for an aggregate price of $19,999,990.00 in an underwritten public offering"

An underwritten public offering is when a company sells new shares of its stock to the public with the help of a financial firm, called an underwriter. The underwriter agrees to buy all the shares upfront, reducing the company's risk, and then sells them to investors. This process helps companies raise money quickly and confidently from a wide range of buyers.

lock-up letter agreement financial

"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"

dispositive power financial

"Fairmount is the investment manager to Fund II and has voting and dispositive power over shares of Common Stock"

Dispositive power is the authority to decide the final outcome of an asset, legal claim, contract, or corporate action — in effect the power to dispose of or resolve something. For investors it matters because whoever holds that authority can determine who gets paid, who controls an asset or vote, and how risks and returns are allocated; think of it like holding the key that lets you lock in the winner or loser in a deal.

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)

92790C104

(CUSIP Number)

Ms. Erin O'Connor
Fairmount Funds Management LLC, 200 Barr Harbor Drive, Suite 400
West Conshohocken, PA, 19428
(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)

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): 92790C104

1

Name of reporting person

Fairmount Funds Management LLC

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)

AF

5

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

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 17,201,800.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 17,201,800.00

11

Aggregate amount beneficially owned by each reporting person

17,201,800.00

12

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

13

Percent of class represented by amount in Row (11)

14.04 %

14

Type of Reporting Person (See Instructions)

IA

Comment for Type of 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.

SCHEDULE 13D

CUSIP Number(s): 92790C104

1

Name of reporting person

Fairmount Healthcare Fund II GP LLC

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)

AF

5

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

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 17,201,800.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 17,201,800.00

11

Aggregate amount beneficially owned by each reporting person

17,201,800.00

12

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

13

Percent of class represented by amount in Row (11)

14.04 %

14

Type of Reporting Person (See Instructions)

PN

Comment for Type of 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.

SCHEDULE 13D

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, MASSACHUSETTS , 02453.
Item 1 Comment: 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 3.	Source and Amount of Funds or Other Consideration
	Item 3 of the Statement is hereby amended and supplemented as follows: In aggregate, the Reporting Persons have voting and dispositive power over 17,201,800 shares of Common Stock, which is comprised of (a) 5,090,928 shares of Common Stock, and (b) an aggregate of 12,110,872.18 (rounded to 12,110,872 shares for purposes of reporting in this Schedule 13D) 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. On May 11, 2026, Fund II purchased a total of 1,176,470 shares of Common Stock for an aggregate price of $19,999,990.00 in an underwritten public offering (the "Offering"). The shares were purchased with working capital. Fairmount and Fairmount GP II do not own any shares of Common Stock, Series A Preferred Stock or Series B Preferred Stock directly. Fairmount and Fairmount GP II are deemed to beneficially own the shares Common Stock, Series A Preferred Stock and Series B Preferred Stock held by Fund II. Fairmount and Fairmount GP II disclaim beneficial ownership of such shares of Common Stock, Series A Preferred Stock and Series B Preferred Stock except to the extent of their pecuniary interest therein.
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.
(d)	Fairmount is the investment manager to Fund II and has voting and dispositive power over shares of Common Stock held on behalf of Fund II. Fairmount GP II serves as the general partner to Fund II and is deemed to share voting and dispositive power over shares of Common Stock held on behalf of Fund II in its capacity as general partner.
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.
Item 7.	Material to be Filed as Exhibits.
	99.1 Joint Filing Agreement (incorporated by reference to Exhibit 99.1 of the Reporting Persons' Schedule 13D filed with the SEC on October 27, 2025). 99.2 Lock-Up Agreement (incorporated by reference to Exhibit A to the Underwriting Agreement filed as Exhibit 1.1 of the Company's Form 8-K filed with the SEC on May 11, 2026).

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.

Fairmount Funds Management LLC

Signature:	/s/ Peter Harwin
Name/Title:	Peter Harwin, Managing Member
Date:	05/13/2026

Signature:	/s/ Tomas Kiselak
Name/Title:	Tomas Kiselak, Managing Member
Date:	05/13/2026

Fairmount Healthcare Fund II GP LLC

Signature:	/s/ Peter Harwin
Name/Title:	Peter Harwin, Managing Member
Date:	05/13/2026

Signature:	/s/ Tomas Kiselak
Name/Title:	Tomas Kiselak, Managing Member
Date:	05/13/2026

FAQ

How much of Viridian Therapeutics (VRDN) does Fairmount now beneficially own?

Fairmount entities report beneficial ownership of 17,201,800 Viridian common shares, representing 14.04% of outstanding common stock as of May 11, 2026. This total includes both existing common shares and shares issuable upon conversion of preferred stock.

What new Viridian Therapeutics (VRDN) shares did Fairmount purchase in May 2026?

On May 11, 2026, Fairmount Healthcare Fund II purchased 1,176,470 Viridian common shares at $17 per share in an underwritten public offering, for an aggregate purchase price of $19,999,990, using the fund’s working capital.

What types of securities make up Fairmount’s Viridian (VRDN) position?

Fairmount’s reported position includes 5,090,928 Viridian common shares plus 12,110,872 common shares issuable upon conversion of Series A and Series B Non-Voting Convertible Preferred Stock, each subject to a 19.99% beneficial ownership limitation.

How was the 14.04% ownership in Viridian (VRDN) calculated for Fairmount?

The 14.04% ownership is based on 122,538,554 Viridian common shares outstanding as of May 11, 2026. This consists of 110,427,682 existing common shares plus 12,110,872 common shares issuable upon conversion of Fairmount-held preferred stock.

Is Fairmount subject to a lock-up on its Viridian Therapeutics (VRDN) shares?

Yes. In connection with the May 11, 2026 offering, Fairmount Healthcare Fund II entered a customary lock-up agreement, agreeing not to sell Viridian securities for 60 days from the date of the company’s final prospectus supplement, absent underwriter consent.

What is the beneficial ownership limitation on Viridian (VRDN) preferred shares held by Fairmount?

The Series A and Series B Non-Voting Convertible Preferred Stock held by Fairmount are each subject to a 19.99% beneficial ownership limitation. This cap restricts conversions so Fairmount’s beneficial ownership of Viridian common stock does not exceed 19.99% outstanding.