Fulcrum Therapeutics (FULC) amendment shows 5.25M-share, 7.9% position

Rhea-AI Filing Summary

Fulcrum Therapeutics files Amendment No. 1 to a previously submitted Schedule 13G, reporting shared voting and dispositive power over 5,250,000 shares of Common Stock. The amendment states this equals 7.9% of the class based on 66,633,321 shares outstanding as of April 20, 2026, and attributes the holdings to TCG Crossover II, its general partner TCG Crossover GP II, and Chen Yu.

The filing clarifies ownership chains and disclaims group status; it amends the original statement filed September 20, 2024, and attaches the joint-filing agreement referenced in the original.

Insights

Institutional Ownership Analyst

Large position disclosed by crossover fund identifies a meaningful passive stake.

The amendment documents that TCG Crossover II and affiliated entities collectively hold 5,250,000 shares, representing 7.9% of the outstanding common stock as of April 20, 2026. The filing attributes shared voting and dispositive power across the fund, GP, and an individual managing member.

The filing is administrative: it clarifies beneficial ownership structure and the joint-filing arrangement under Rule 13d-1(k)(1). Subsequent public disclosures would be required only if holdings cross reporting thresholds or change materially.

Corporate Governance Specialist

Clarifies control lines and disclaims group status while confirming fund-level influence.

The statement explains that voting and dispositive powers are shared and that Chen Yu, as sole managing member of the GP, may be deemed to share those powers. The Reporting Persons expressly disclaim group status for this filing.

Key dependencies include the issuer's outstanding share count cited from the Form 10-Q. Any change in voting arrangements or transfers would require amendment filings to update the public record.

Key Figures

Shares beneficially owned (shared): 5,250,000 shares Percent of class: 7.9% Shares outstanding (issuer): 66,633,321 shares +1 more

4 metrics

Shares beneficially owned (shared) 5,250,000 shares shared voting and dispositive power reported on Amendment No. 1

Percent of class 7.9% based on 66,633,321 shares outstanding as of April 20, 2026

Shares outstanding (issuer) 66,633,321 shares as of April 20, 2026, cited from issuer's Form 10-Q

CUSIP 359616109 Fulcrum Therapeutics Common Stock CUSIP on the filing cover

Key Terms

beneficial ownership, shared dispositive power, Rule 13d-1(k)(1)

3 terms

beneficial ownership regulatory

"These securities are held of record by TCG Crossover II"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

shared dispositive power regulatory

"Shared Dispositive Power 5,250,000.00"

Rule 13d-1(k)(1) regulatory

"joint-filing agreement in accordance with the provisions of Rule 13d-1(k)(1)"

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 05/15/2026 - 04:26 PM Learn about SEC filing dates

FAQ

What stake does TCG Crossover II report in FULC?

The filing reports shared voting and dispositive power over 5,250,000 shares, equal to 7.9% of common stock. This percentage uses 66,633,321 shares outstanding as of April 20, 2026 from the issuer's Form 10-Q.

Who are the reporting persons on this Schedule 13G/A for FULC?

The reporting persons are TCG Crossover Fund II, L.P., its general partner TCG Crossover GP II, LLC, and Chen Yu, identified as the sole managing member of the GP and a related reporting individual.

Does the filing claim coordinated group status for these holders?

No. The amendment explicitly states the Reporting Persons expressly disclaim status as a group for purposes of the Schedule 13G and attaches the joint-filing agreement referenced in the original filing.

What voting and dispositive powers are reported?

Each Reporting Person reports 0 sole voting/dispositive power and 5,250,000 shared voting and dispositive power, reflecting the holdings recorded as held of record by TCG Crossover II.

What source is used for the shares outstanding figure?

The filing cites the issuer's quarterly report on Form 10-Q filed April 27, 2026 for the figure of 66,633,321 shares outstanding as of April 20, 2026 used to calculate the 7.9% ownership percentage.

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)

03/31/2026

(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

TCG Crossover GP II, 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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 5,250,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 5,250,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

5,250,000.00

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)

7.9 %

12

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person: These securities are held of record by TCG Crossover II (as defined in Item 2(a) below). TCG Crossover GP II (as defined in Item 2(a) below) is the general partner of TCG Crossover II and may be deemed to have voting, investment, and dispositive power with respect to these securities. Chen Yu is the sole managing member of TCG Crossover GP II and may be deemed to share voting, investment and dispositive power with respect to these securities. Based on 66,633,321 shares of Common Stock outstanding as of April 20, 2026, as reported by the Issuer (as defined in Item 1(a) below) in its quarterly report on Form 10-Q filed with the Securities and Exchange Commission (the "Commission") on April 27, 2026 (the "Form 10-Q").

SCHEDULE 13G

CUSIP Number(s): 359616109

1

Names of Reporting Persons

TCG Crossover Fund II, L.P.

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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 5,250,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 5,250,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

5,250,000.00

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)

7.9 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: These securities are held of record by TCG Crossover II. TCG Crossover GP II is the general partner of TCG Crossover II and may be deemed to have voting, investment, and dispositive power with respect to these securities. Chen Yu is the sole managing member of TCG Crossover GP II and may be deemed to share voting, investment and dispositive power with respect to these securities. Based on 66,633,321 shares of Common Stock outstanding as of April 20, 2026, as reported by the Issuer in the Form 10-Q.

SCHEDULE 13G

CUSIP Number(s): 359616109

1

Names of Reporting Persons

Chen Yu

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 5,250,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 5,250,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

5,250,000.00

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)

7.9 %

12

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person: These securities are held of record by TCG Crossover II. TCG Crossover GP II is the general partner of TCG Crossover II and may be deemed to have voting, investment, and dispositive power with respect to these securities. Chen Yu is the sole managing member of TCG Crossover GP II and may be deemed to share voting, investment and dispositive power with respect to these securities. Based on 66,633,321 shares of Common Stock outstanding as of April 20, 2026, as reported by the Issuer in the Form 10-Q.

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Fulcrum Therapeutics, Inc.
(b)	Address of issuer's principal executive offices: 26 Landsdowne Street, Cambridge, MA 02139
Item 2.
(a)	Name of person filing: This Amendment No. 1 (Amendment No. 1) amends and supplements the Schedule 13G initially filed with the Commission on September 20, 2024 (the Original Schedule 13G) and is being filed by TCG Crossover Fund II, L.P. (TCG Crossover II), TCG Crossover GP II, LLC (TCG Crossover GP II, and together with TCG Crossover II, the Reporting Entities) and Chen Yu (the Reporting Individual). The Reporting Entities and the Reporting Individual are collectively referred to as the Reporting Persons. The Reporting Persons expressly disclaim status as a group for purposes of this Schedule 13G. The agreement among the Reporting Persons to file jointly in accordance with the provisions of Rule 13d-1(k)(1) under the Act is attached as Exhibit 1 to the Original Schedule 13G. Other than those securities reported herein as being held directly by such Reporting Person, each Reporting Person disclaims beneficial ownership of all securities reported in this Statement except to the extent of such Reporting Person's pecuniary interest therein. Capitalized terms not defined in this Amendment No. 1 have the meanings ascribed to them in the Original Schedule 13G.
(b)	Address or principal business office or, if none, residence: The address of the principal business office of each Reporting Person is 245 Lytton Ave., Suite 350, Palo Alto, CA 94301.
(c)	Citizenship: TCG Crossover GP II is a limited liability company organized under the laws of the State of Delaware. TCG Crossover II is a limited partnership organized under the laws of the State of Delaware. The Reporting Individual 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: See Row 9 of the cover page for each Reporting Person and the corresponding comments.
(b)	Percent of class: See Row 11 of the cover page for each Reporting Person and the corresponding comments.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: See Row 5 of the cover page for each Reporting Person and the corresponding comments.
	(ii) Shared power to vote or to direct the vote: See Row 6 of the cover page for each Reporting Person and the corresponding comments.
	(iii) Sole power to dispose or to direct the disposition of: See Row 7 of the cover page for each Reporting Person and the corresponding comments.
	(iv) Shared power to dispose or to direct the disposition of: See Row 8 of the cover page for each Reporting Person and the corresponding comments.
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.
	Not Applicable
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 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.

TCG Crossover GP II, LLC

Signature:	/s/ Craig Skaling
Name/Title:	Craig Skaling, Authorized Signatory
Date:	05/15/2026

TCG Crossover Fund II, L.P.

Signature:	/s/ Craig Skaling
Name/Title:	Craig Skaling, Authorized Signatory
Date:	05/15/2026

Chen Yu

Signature:	/s/ Craig Skaling
Name/Title:	Craig Skaling, as Attorney-in-Fact for Chen Yu
Date:	05/15/2026