EcoR1 reports 9.0% stake in Fulcrum Therapeutics

Fulcrum Therapeutics reports large passive holdings by EcoR1 and affiliated parties.

Rhea-AI Filing Summary

Fulcrum Therapeutics reports large passive holdings by EcoR1 and affiliated parties. EcoR1 Capital, LLC and Oleg Nodelman each report beneficial ownership of 6,000,000 shares (listed as 9.0% of common stock), and EcoR1 Capital Fund Qualified, L.P. reports 5,614,199 shares (8.4%), with percentages calculated using 66,633,321 shares outstanding as of April 20, 2026. The filing states shared voting and dispositive power for the reported holdings and includes a joint-filing agreement; the reporting persons disclaim group status and certain beneficial ownership beyond pecuniary interests.

Insights

Corporate Governance Analyst

EcoR1 and its principal report single-digit stakes that could influence engagement rather than control.

The filing shows shared voting and dispositive power over 6,000,000 shares for EcoR1 and Mr. Nodelman, representing 9.0% of the class based on 66,633,321 shares outstanding as of April 20, 2026. This level typically permits active engagement but does not imply control.

Future filings may disclose any changes in voting arrangements or plans; cash-flow treatment and intent beyond the disclosed statement are not included in the excerpt.

Institutional Investor Specialist

Holdings are material at the holder level but below majority thresholds; they warrant monitoring for engagement activity.

The excerpt quantifies holdings—6,000,000 shares and 5,614,199 shares—and explicitly attributes shared power for voting and disposition. The filing includes a joint-filing agreement and a disclaimer against group status.

Watch for amendments or Schedule 13D conversions that would signal active campaign or control-seeking; timing and intent are not stated here.

Key Figures

EcoR1 holdings: 6,000,000 shares Nodelman holdings: 6,000,000 shares Qualified Fund holdings: 5,614,199 shares +3 more

6 metrics

EcoR1 holdings 6,000,000 shares Beneficially owned by EcoR1 Capital, LLC

Nodelman holdings 6,000,000 shares Beneficially owned by Oleg Nodelman (shared power)

Qualified Fund holdings 5,614,199 shares EcoR1 Capital Fund Qualified, L.P.

Percent of class (EcoR1/Nodelman) 9.0% Percentage calculated using 66,633,321 shares outstanding as of April 20, 2026

Percent of class (Qualified Fund) 8.4% Percentage calculated using 66,633,321 shares outstanding as of April 20, 2026

Shares outstanding reference 66,633,321 shares Used as the denominator for percentage calculations (April 20, 2026)

Key Terms

Schedule 13G, Shared Dispositive Power, Beneficial Ownership

3 terms

Schedule 13G regulatory

"Item 1. | (a) | Name of issuer: Fulcrum Therapeutics, Inc."

A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.

Shared Dispositive Power financial

"6 | Shared Dispositive Power 6,000,000.00"

Beneficial Ownership regulatory

"Item 4. | Ownership (a) | Amount beneficially owned: EcoR1: 6,000,000"

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.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What stake does EcoR1 report in Fulcrum Therapeutics (FULC)?

EcoR1 Capital, LLC reports beneficial ownership of 6,000,000 shares, equal to 9.0% of common stock. The percentage uses 66,633,321 shares outstanding as of April 20, 2026, per the filing's stated calculation.

How much does Oleg Nodelman personally report owning in FULC?

Oleg Nodelman reports beneficial ownership of 6,000,000 shares, shown as 9.0% of the class based on the filing's stated outstanding share figure of 66,633,321 as of April 20, 2026.

What stake does EcoR1 Capital Fund Qualified, L.P. report in Fulcrum?

EcoR1 Capital Fund Qualified, L.P. reports beneficial ownership of 5,614,199 shares, equal to 8.4% of common stock using the filing's stated outstanding share base of 66,633,321 as of April 20, 2026.

Do the reporting persons claim control of Fulcrum Therapeutics?

The filing includes a joint-filing agreement and a signed certification stating the securities were not acquired to change or influence control. It also disclaims membership in a group and certain beneficial ownership beyond pecuniary interest.

What voting and disposition powers are disclosed for these holdings?

The entities report 0 sole voting/dispositive power and shared voting and shared dispositive power for the reported shares (6,000,000 and 5,614,199 respectively), as stated in the ownership table of the filing.

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

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Accepted by SEC EDGAR 06/25/2026 - 06:10 PM EDT Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Fulcrum Therapeutics, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

359616109

(CUSIP Number)

06/17/2026

(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

EcoR1 Capital, 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 6,000,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 6,000,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

6,000,000.00

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)

9.0 %

12

Type of Reporting Person (See Instructions)

IA, OO

Comment for Type of Reporting Person: Percentage calculated based on 66,633,321 shares of Common Stock outstanding on April 20, 2026, as reported in the Form 10-Q filed by the Issuer for the quarterly period ended March 31, 2026.

SCHEDULE 13G

CUSIP Number(s): 359616109

1

Names of Reporting Persons

Oleg Nodelman

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 6,000,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 6,000,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

6,000,000.00

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)

9.0 %

12

Type of Reporting Person (See Instructions)

HC, IN

Comment for Type of Reporting Person: Percentage calculated based on 66,633,321 shares of Common Stock outstanding on April 20, 2026, as reported in the Form 10-Q filed by the Issuer for the quarterly period ended March 31, 2026.

SCHEDULE 13G

CUSIP Number(s): 359616109

1

Names of Reporting Persons

EcoR1 Capital Fund Qualified, 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 5,614,199.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 5,614,199.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

5,614,199.00

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)

8.4 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: Percentage calculated based on 66,633,321 shares of Common Stock outstanding on April 20, 2026, as reported in the Form 10-Q filed by the Issuer for the quarterly period ended March 31, 2026.

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: EcoR1 Capital, LLC, a Delaware limited liability company ("EcoR1") EcoR1 Capital Fund Qualified, L.P., a Delaware limited partnership ("Qualified Fund") Oleg Nodelman Qualified Fund is filing this statement jointly with the other reporting persons, but not as a member of a group, and it expressly disclaims membership in a group. In addition, the filing of this Schedule 13G on behalf of Qualified Fund should not be construed as an admission that it is, and it disclaims that it is, a beneficial owner, as defined in Rule 13d-3 under the Act, of any securities covered by this Schedule 13G. Each reporting person also disclaims beneficial ownership of the securities reported herein except to the extent of that person's pecuniary interest therein.
(b)	Address or principal business office or, if none, residence: 357 Tehama Street #3 San Francisco, CA 94103
(c)	Citizenship: See Item 4 of the cover sheet for each reporting person.
(d)	Title of class of securities: Common Stock
(e)	CUSIP Number(s): 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: EcoR1: 6,000,000 Oleg Nodelman: 6,000,000 Qualified Fund: 5,614,199
(b)	Percent of class: EcoR1: 9.0% Oleg Nodelman: 9.0% Qualified Fund: 8.4%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: EcoR1: 0 Oleg Nodelman: 0 Qualified Fund: 0
	(ii) Shared power to vote or to direct the vote: EcoR1: 6,000,000 Oleg Nodelman: 6,000,000 Qualified Fund: 5,614,199
	(iii) Sole power to dispose or to direct the disposition of: EcoR1: 0 Oleg Nodelman: 0 Qualified Fund: 0
	(iv) Shared power to dispose or to direct the disposition of: EcoR1: 6,000,000 Oleg Nodelman: 6,000,000 Qualified Fund: 5,614,199
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.
	If a group has filed this schedule pursuant to §240.13d-1(b)(1)(ii)(K), so indicate under Item 3(k) and attach an exhibit stating the identity and Item 3 classification of each member of the group. If a group has filed this schedule pursuant to §240.13d-1(c) or §240.13d-1(d), attach an exhibit stating the identity of each member of the group. EcoR1 is the general partner and investment adviser of investment funds, including Qualified Fund. Mr. Nodelman is the control person of EcoR1.
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. 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.

EcoR1 Capital, LLC

Signature:	/s/ Oleg Nodelman
Name/Title:	Manager
Date:	06/25/2026

Oleg Nodelman

Signature:	/s/ Oleg Nodelman
Name/Title:	Reporting person
Date:	06/25/2026

EcoR1 Capital Fund Qualified, L.P.

Signature:	/s/ Oleg Nodelman
Name/Title:	Manager of the General Partner, EcoR1 Capital, LLC
Date:	06/25/2026

Exhibit Information

EXHIBIT 99 - AGREEMENT REGARDING JOINT FILING OF STATEMENT ON SCHEDULE 13D OR 13G