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Fulcrum Therapeutics, Inc. (FULC) reports that Nantahala Capital Management, LLC may be deemed beneficial owner of 6,575,352 shares as of September 30, 2026. Managing members Wilmot B. Harkey and Daniel Mack may each also be deemed beneficial owners of those same shares. Each reporting person’s reported beneficial ownership was 8.62% of the class.
Each reported shared voting and shared dispositive power over 6,575,352 shares and sole voting and dispositive power over 0 shares. The shares are held by funds and separately managed accounts under Nantahala’s control.
Key Figures
Beneficial ownership:6,575,352 sharesPercent of class:8.62%Shared voting power:6,575,352 shares+2 more
5 metrics
Beneficial ownership6,575,352 sharesReported for each reporting person as of September 30, 2026; the amount refers to the same shares, not separate holdings.
Percent of class8.62%Reported for each reporting person as of September 30, 2026.
Shared voting power6,575,352 sharesReported for each reporting person as of September 30, 2026.
Shared dispositive power6,575,352 sharesReported for each reporting person as of September 30, 2026.
Sole voting and dispositive power0 sharesReported for each reporting person as of September 30, 2026.
"may be deemed to be the beneficial owner of 6,575,352 Shares"
A beneficial owner is the person who ultimately owns or controls a financial asset or property, even if their name isn't directly on official documents. Think of it like someone who secretly holds the keys to a safe deposit box—others may appear to have access, but the true owner is the one who benefits from what's inside. Identifying beneficial owners helps ensure transparency and prevent illegal activities like money laundering or fraud.
shared voting powertechnical
"Shared power to vote or to direct the vote"
Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.
shared dispositive powertechnical
"Shared power to dispose or to direct the disposition"
investment advisertechnical
"Nantahala, an investment adviser"
An investment adviser is a person or firm that professionally manages money and gives recommendations about buying, selling, or holding investments. Like a financial coach or guide, they have a legal duty to act in a client's best financial interest, so their advice, fees and potential conflicts can directly affect returns and risk — making their role important for investors who want informed, accountable help with portfolios.
FAQ
AI-generated questions and answers. How Rhea-AI works. Not financial advice.
How many FULC shares did Nantahala report beneficially owning?
Nantahala Capital Management, LLC may be deemed beneficial owner of 6,575,352 shares as of September 30, 2026, equal to 8.62% of the class. The shares are held by funds and separately managed accounts under Nantahala’s control.
What voting and disposition powers were reported for the FULC shares?
Nantahala Capital Management, LLC, Wilmot B. Harkey and Daniel Mack each reported shared voting and shared dispositive power over 6,575,352 shares, and sole voting and dispositive power over 0 shares.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
(Amendment No. 1)
FULCRUM THERAPEUTICS, INC.
(Name of Issuer)
Common stock, par value $0.001 per share
(Title of Class of Securities)
359616109
(CUSIP Number)
09/30/2026
(Date of Event Which Requires Filing of this Statement)
Check the appropriate box to designate the rule pursuant to which this Schedule is filed:
Rule 13d-1(b)
Rule 13d-1(c)
Rule 13d-1(d)
schemaVersion:
SCHEDULE 13G
CUSIP Number(s):
359616109
1
Names of Reporting Persons
Nantahala Capital Management, LLC
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
MASSACHUSETTS
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
6,575,352.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
6,575,352.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
6,575,352.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
8.62 %
12
Type of Reporting Person (See Instructions)
IA
SCHEDULE 13G
CUSIP Number(s):
359616109
1
Names of Reporting Persons
Wilmot B. Harkey
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
UNITED STATES
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
6,575,352.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
6,575,352.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
6,575,352.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
8.62 %
12
Type of Reporting Person (See Instructions)
HC
SCHEDULE 13G
CUSIP Number(s):
359616109
1
Names of Reporting Persons
Daniel Mack
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
UNITED STATES
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
6,575,352.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
6,575,352.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
6,575,352.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
8.62 %
12
Type of Reporting Person (See Instructions)
HC
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
FULCRUM THERAPEUTICS, INC.
(b)
Address of issuer's principal executive offices:
26 LANDSDOWNE STREET CAMBRIDGE, MASSACHUSETTS, 02139
Item 2.
(a)
Name of person filing:
(1) Nantahala Capital Management, LLC ("Nantahala")
(2) Wilmot B. Harkey
(3) Daniel Mack (together the "Reporting Persons")
(b)
Address or principal business office or, if none, residence:
130 Main St. 2nd Floor, New Canaan, Connecticut 06840
(c)
Citizenship:
(1) Nantahala is a Massachusetts limited liability company.
(2) Each of Messrs. Harkey and Mack is a citizen of the United States of America.
(d)
Title of class of securities:
Common stock, par value $0.001 per share
(e)
CUSIP No.:
359616109
Item 3.
If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)
Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)
Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)
Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)
Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)
An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)
An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)
A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)
A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)
A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)
A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
please specify the type of institution:
(k)
Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.
Ownership
(a)
Amount beneficially owned:
As of September 30, 2026, Nantahala may be deemed to be the beneficial owner of 6,575,352 Shares held by funds and separately managed accounts under its control, and as the managing members of Nantahala, each of Messrs. Harkey and Mack may be deemed to be a beneficial owner of those Shares.
(b)
Percent of class:
As of September 30, 2026, each of the Reporting Persons may be deemed to be the beneficial owner of the following percentage of the total number of Shares outstanding:
(1) Nantahala Capital Management, LLC ("Nantahala") : 8.62%
(2) Wilmot B. Harkey: 8.62%
(3) Daniel Mack: 8.62%
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
(1) Nantahala Capital Management, LLC ("Nantahala") : 0 Shares.
(2) Wilmot B. Harkey: 0 Shares.
(3) Daniel Mack: 0 Shares.
(ii) Shared power to vote or to direct the vote:
(1) Nantahala Capital Management, LLC ("Nantahala") : 6,575,352 Shares.
(2) Wilmot B. Harkey: 6,575,352 Shares.
(3) Daniel Mack: 6,575,352 Shares.
(iii) Sole power to dispose or to direct the disposition of:
(1) Nantahala Capital Management, LLC ("Nantahala") : 0 Shares.
(2) Wilmot B. Harkey: 0 Shares.
(3) Daniel Mack: 0 Shares.
(iv) Shared power to dispose or to direct the disposition of:
(1) Nantahala Capital Management, LLC ("Nantahala") : 6,575,352 Shares.
(2) Wilmot B. Harkey: 6,575,352 Shares.
(3) Daniel Mack: 6,575,352 Shares.
Item 5.
Ownership of 5 Percent or Less of a Class.
Not Applicable
Item 6.
Ownership of more than 5 Percent on Behalf of Another Person.
Not Applicable
Item 7.
Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary.
Each of Messrs. Harkey and Mack is filing this Schedule 13G as a control person in respect of shares beneficially owned by Nantahala, an investment adviser as described in ss. 240.13d-1(b)(1)(ii)(E). See Item 4(a).
Item 8.
Identification and Classification of Members of the Group.
Not Applicable
Item 9.
Notice of Dissolution of Group.
Not Applicable
Item 10.
Certifications:
By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.
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.
Nantahala Capital Management, LLC
Signature:
/s/ Taki Vasilakis
Name/Title:
Taki Vasilakis / Chief Compliance Officer
Date:
11/13/2026
Wilmot B. Harkey
Signature:
/s/ Taki Vasilakis, attorney-in-fact for
Name/Title:
Wilmot B. Harkey
Date:
11/13/2026
Daniel Mack
Signature:
/s/ Taki Vasilakis, attorney-in-fact for
Name/Title:
Daniel Mack
Date:
11/13/2026
Exhibit Information
Exhibit 24 - Power of Attorney incorporated by reference to the November 13, 2026 filing. https://www.sec.gov/Archives/edgar/data/1502725/000110465926127115/0001104659-26-127115-index.htm.
