[SCHEDULE 13G/A] Y-mAbs Therapeutics, Inc. SEC Filing

Rhea-AI Filing Summary

Schedule 13G/A filed for Y-mAbs Therapeutics, Inc. (YMAB) discloses beneficial ownership by Acorn-related entities and Anders Hove. Anders Hove is reported to beneficially own 3,096,297 shares, representing 7.0% of the outstanding common stock based on 45,438,420 shares outstanding as of August 4, 2025. Acorn Bioventures, L.P. and Acorn Capital Advisors GP, LLC each report 1,301,686 shares (3.0%). Acorn Bioventures 2, L.P. and its GP report 1,794,611 shares (4.0%). The filing states these holdings were not acquired to influence control of the issuer and identifies Anders Hove as Manager of the reporting entities. All filers are organized in Delaware except Hove, a U.S. citizen.

Positive

• Anders Hove beneficially owns 3,096,297 shares (7.0%), exceeding the 5% disclosure threshold and providing clear, material ownership transparency
• Acorn entities disclosed aggregate positions with specific shared voting and dispositive powers, improving investor visibility
• Filing contains certification that holdings are not intended to influence control, which clarifies current intent

Negative

• None.

Insights

Securities Analyst

TL;DR: A 7.0% beneficial stake by an individual manager signals a meaningful ownership position but the filing asserts no intent to change control.

Anders Hove is disclosed as the beneficial owner of 3,096,297 shares, equal to 7.0% of outstanding stock, which exceeds the 5% reporting threshold and is material to investors monitoring ownership concentration. The Acorn entities report additional holdings (3.0% and 4.0%) and common voting/dispositive power. The filing includes the required certifications that the positions are not held to influence control, which constrains immediate governance implications but warrants monitoring for future Schedule 13D activity.

Corporate Governance Expert

TL;DR: Combined disclosures show concentrated ownership among related entities and an individual manager, but no stated activist intent.

The filing identifies related limited partnerships and GP entities with shared voting and dispositive power and clarifies managerial relationships. The explicit certification that securities were not acquired to influence control reduces near-term governance alarm, yet the presence of a 7.0% holder who is manager of the GPs is governance-relevant and should be tracked for any subsequent changes in intent or additional filings.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 2)

Y-mAbs Therapeutics, Inc.

(Name of Issuer)

Common stock, par value $0.0001 per share

(Title of Class of Securities)

984241109

(CUSIP Number)

08/14/2025

(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)

SCHEDULE 13G

CUSIP No. 984241109

1

Names of Reporting Persons

ACORN BIOVENTURES, 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 1,301,686.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,301,686.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,301,686.00

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)

3.0 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

CUSIP No. 984241109

1

Names of Reporting Persons

ACORN CAPITAL ADVISORS GP, 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 1,301,686.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,301,686.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,301,686.00

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)

3.0 %

12

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13G

CUSIP No. 984241109

1

Names of Reporting Persons

ACORN BIOVENTURES 2, 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 1,794,611.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,794,611.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,794,611.00

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)

4.0 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

CUSIP No. 984241109

1

Names of Reporting Persons

Acorn Capital Advisors GP 2, 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 1,794,611.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,794,611.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,794,611.00

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)

4.0 %

12

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13G

CUSIP No. 984241109

1

Names of Reporting Persons

Anders Hove

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 3,096,297.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 3,096,297.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,096,297.00

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)

7.0 %

12

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Y-mAbs Therapeutics, Inc.
(b)	Address of issuer's principal executive offices: 202 CARNEGIE CENTER, SUITE 301, PRINCETON, NEW JERSEY, 08540.
Item 2.
(a)	Name of person filing: Acorn Bioventures, L.P. Acorn Capital Advisors GP, LLC Acorn Bioventures 2, L.P. Acorn Capital Advisors GP 2, LLC Anders Hove
(b)	Address or principal business office or, if none, residence: 420 Lexington Avenue, Suite 2626, New York, New York 10170
(c)	Citizenship: Acorn Bioventures, L.P. and Acorn Bioventures 2 L.P. are both Delaware limited partnerships. Acorn Capital Advisors GP, LLC and Acorn Capital Advisors GP 2, LLC are both Delaware limited liability companies. Anders Hove is a citizen of the United States of America.
(d)	Title of class of securities: Common stock, par value $0.0001 per share
(e)	CUSIP No.: 984241109
Item 4.	Ownership
(a)	Amount beneficially owned: The information required by Items 4(a) - (c) is set forth in Rows (5) - (11) of the cover page for each Reporting Person hereto and is incorporated herein by reference for each Reporting Person.
(b)	Percent of class: The percentages set forth herein are calculated based upon 45,438,420 shares of Common Stock outstanding as of August 4, 2025 as reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2025 filed with the Securities and Exchange Commission on August 8, 2025.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: Acorn Capital Advisors GP, LLC is the General Partner of Acorn Bioventures, LP and may be deemed to beneficially own the shares of Common Stock beneficially owned by Acorn Bioventures, LP. Acorn Capital Advisors GP 2, LLC is the General Partner of Acorn Bioventures 2, L.P. and may be deemed to beneficially own the shares of Common Stock beneficially owned by Acorn Bioventures 2, L.P.
	(ii) Shared power to vote or to direct the vote: Anders Hove, in his capacity as Manager of each of Acorn Capital Advisors GP, LLC and Acorn Capital Advisors GP 2, LLC, may be deemed to beneficially own the shares beneficially owned by each of Acorn Capital Advisors GP, LLC and Acorn Capital Advisors GP 2, LLC.
	(iii) Sole power to dispose or to direct the disposition of:
	(iv) Shared power to dispose or to direct the disposition of:
Item 5.	Ownership of 5 Percent or Less of a Class.
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.

ACORN BIOVENTURES, L.P.

Signature:	Anders Hove
Name/Title:	Manager of General Partner
Date:	08/15/2025

ACORN CAPITAL ADVISORS GP, LLC

Signature:	Anders Hove
Name/Title:	Manager
Date:	08/15/2025

ACORN BIOVENTURES 2, L.P.

Signature:	Anders Hove
Name/Title:	Manager of General Partner
Date:	08/15/2025

Acorn Capital Advisors GP 2, LLC

Signature:	Anders Hove
Name/Title:	Manager
Date:	08/15/2025

Anders Hove

Signature:	Anders Hove
Name/Title:	Individually
Date:	08/15/2025

FAQ

How many Y-mAbs (YMAB) shares does Anders Hove beneficially own?

The filing reports Anders Hove beneficially owns 3,096,297 shares, representing 7.0% of common stock based on 45,438,420 shares outstanding.

What percentages of YMAB does Acorn Bioventures and Acorn Bioventures 2 hold?

Acorn Bioventures, L.P. reports 1,301,686 shares (3.0%) and Acorn Bioventures 2, L.P. reports 1,794,611 shares (4.0%).

Do the filers state any intent to influence control of Y-mAbs?

Yes. The filing includes a certification that the securities were not acquired and are not held to change or influence control of the issuer.

Who is the contact/manager identified for the reporting entities?

Anders Hove is identified as Manager of the general partner entities and signed the filing individually and on behalf of the entities.

What population of shares was used to calculate the ownership percentages?

Percentages are calculated using 45,438,420 shares outstanding as of August 4, 2025, per the issuer's quarterly report for the period ended June 30, 2025.