EcoR1 Capital (FULC) reports shared control of 6.0M shares; 9.0% stake

Rhea-AI Filing Summary

EcoR1 Capital and related persons report beneficial ownership of Fulcrum Therapeutics common stock. The filing states EcoR1 Capital, LLC and Oleg Nodelman each have shared voting and dispositive power over 6,000,000 shares (reported as 9.0% of the class). It also shows EcoR1 Capital Fund Qualified, L.P. holds 5,614,199 shares (reported as 8.4%). The percentages are calculated using 66,633,321 shares outstanding as of April 20, 2026, per the issuer's Form 10-Q for the quarter ended March 31, 2026. The filing includes a joint-filing agreement and statements disclaiming group membership beyond the reporting relationship.

Insights

Activist / Institutional Investor Analyst

EcoR1 and Oleg Nodelman report double-digit single-holder stakes by percentage terms.

EcoR1 Capital, LLC and Oleg Nodelman are each reported with shared voting and dispositive power over 6,000,000 shares (9.0%). The filing clarifies the reporting structure and attributes 5,614,199 shares to a Qualified Fund that EcoR1 manages.

The disclosed percentages use 66,633,321 shares outstanding as of April 20, 2026. The filing contains a joint-filing agreement and disclaimers about group membership; cash-flow treatment or planned transactions are not stated in the excerpt.

Corporate Governance Specialist

Filing documents shared control and formal reporting relationships, not a change of control transaction.

The schedule lists shared voting and dispositive power rather than sole power, and includes an express disclaimer that the reporting persons do not file as a group for control purposes. This frames the disclosure as ownership transparency, not an explicit control initiative.

Investors may track subsequent filings for any changes; the excerpt does not state any planned nominations, agreements to change control, or transactions.

Key Figures

EcoR1 / Nodelman reported shares: 6,000,000 shares Qualified Fund reported shares: 5,614,199 shares Percent of class (EcoR1 / Nodelman): 9.0% +2 more

5 metrics

EcoR1 / Nodelman reported shares 6,000,000 shares shared voting and dispositive power

Qualified Fund reported shares 5,614,199 shares EcoR1 Capital Fund Qualified, L.P. beneficial ownership

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

Percent of class (Qualified Fund) 8.4% based on 66,633,321 shares outstanding as of April 20, 2026

Shares outstanding used for calculation 66,633,321 shares as of April 20, 2026 per issuer Form 10-Q (quarter ended March 31, 2026)

Key Terms

Schedule 13G, shared dispositive power, beneficially owned, joint-filing agreement

4 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"

beneficially owned regulatory

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

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

joint-filing agreement regulatory

"Exhibit 99 - AGREEMENT REGARDING JOINT FILING"

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

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Available on EDGAR 06/25/2026 - 05:51 PM Accepted by SEC EDGAR 06/25/2026 - 05:51 PM Learn about SEC filing dates

FAQ

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

EcoR1 Capital and Oleg Nodelman report shared power over 6,000,000 shares, equal to 9.0% of the class, per the filing. The percentage is calculated using 66,633,321 shares outstanding as of April 20, 2026.

How many shares does EcoR1 Capital Fund Qualified, L.P. report owning in FULC?

The filing reports 5,614,199 shares beneficially owned by EcoR1 Capital Fund Qualified, L.P., representing 8.4% of the class. The calculation uses the issuer's outstanding share count dated April 20, 2026.

Does this Schedule 13G state EcoR1 intends to change control of Fulcrum Therapeutics?

No. The signatory certifies the securities were not acquired to change control and the filing includes disclaimers that the reporting persons are not filing as a control group beyond reporting relationships.

What outstanding share count is used to compute the reported percentages for FULC?

The percentages are calculated based on 66,633,321 shares outstanding as of April 20, 2026, as reported in the issuer's Form 10-Q for the quarter ended March 31, 2026.

Who signed the Schedule 13G for these reporting persons?

The document is signed by Oleg Nodelman in multiple capacities (Manager and Reporting Person) with signature dates shown as 06/25/2026 in the filing excerpt.

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